What I usually see in pictures has her sitting sideways in his arms hanging onto his shoulders/neck; that’s pretty close to the core, all things considered.
For myself though I find it pretty hard to carry women, as a man - they keep refusing, and give me funny looks when I ask.
My back being what it is these days, it’s a no go for me.
But, before that, I’ve found the easiest way was to let the girl drape one arm over your shoulder and then jump! Letting the guy catch you.
The “dead lift” is the hard part. Once erect, everything else is easy.
We’re talking the same pose, but her legs & opposite shoulder are not as near to his core as with ‘piggy’ carrying.
A 180 lb man deadlifting 160 lbs might not be possible but the woman isn’t going to be dead weight (hopefully). She can help him lift her and put her arms around him to help keep herself up and balanced. I think once she’s in his arms, it’s more of an issue of keeping it all together for a few steps.
If all else fails, fireman’s carry.
They should practice.
I wondered this a while back while watching a Doctor Who episode where David Tennant is carrying Freema Agyeman (Martha) in his arms. He’s a pretty slim dude and doesn’t look like he works out, but he didn’t seem to have much trouble with it. According to the celebrity sites, he’s 6’1" and 161 lbs, and she’s 5’2" and 120.
Picking up a 120-pound woman to carry a short distance wouldn’t be that hard. My wife might weigh 130, and I am pretty confident I could carry her long enough to make an impression on camera. I’ve picked her up before. I am not very strong.
But could I carry her, say, a hundred metres? That’d be tough. Maybe in a fireman’s carry, but just in my arms? I doubt it.
It’s easy to lift a girl if she cooperating. Getting her through a doorway is trickier, but still not a huge deal. They could always do a practice carry or two if the guy is worried about it.
I did it without any trouble on our wedding day, but she was probably twenty pounds lighter than your friend then. She’s closer to that weight new, but I think I could do it. I’m almost the same size as her betrothed, but in my fifties.
I suspect most girlfriends can carry their guys, too. It’s mostly a matter of balance and being able to support some weight in your legs. You don’t carry people using your arms and shoulders; if you do, you’re not doing it right.
“Live” weight is much easier to carry than “dead.” I once worked with a little boy with muscular dystrophy who probably weighted only 40lbs or so, but he felt very heavy, because he was limp, and did nothing to assist being lifted (because he couldn’t). I could still lift my son when he was twice as heavy, and that was with pregnancy-induced back problems (that I finally saw a PT about and no longer have).
Carrying something close to your body is key.
In Basic Training, we had to do a move where we had our rifles on our shoulders, moved them to our front, pulled back the charging handle, slapped the butt, and moved them back to our shoulders. I was the only one who could do it the first time. It wasn’t strength. I just knew to keep the rifle as close to my body as possible, so I was using my deltoids and biceps. All the other women, apparently afraid of the noise, or just not understanding what they were supposed to do, were holding the rifles too far out in front of themselves, and using their forearm and wrist muscles.
The drill sergeants made me stand in front of the platoon and demonstrate.
Anyway, you want to be using as many muscles as possible, and especially using your big muscles. If the person leans against you, and puts her (or his) arms around your shoulders, you will be using lats, deltoids, obliques, and abs, and your biceps and triceps will be cradling, not holding up against gravity. You want your arms as close to your own body as possible. Carrying a person is not like carrying a bag of cement. A 70lb. bag of cement feels heavier than a 140lb. person.
When my aunt was ill, I could lift her. She weighed more than I did, by maybe 15lbs. I didn’t walk around with her in my arms, in a threshold carry, just transferred her from bed, to wheelchair, to car, etc. but she couldn’t put much weight on her own feet, so she was leaning against my core and chest, with her arms around my neck. I did it without a transfer belt. I was 5’5, about 135lbs., and she was about 5’6, 150lbs. Now, I used to work out, so I was stronger than most women, but still, I think if I could do that, a man who was significantly larger than I was could also do it, even if he didn’t work out, as long as he didn’t have back problems.
Humorous note: in the 1941 Dr. Jekyll & Mr. Hyde, Spencer Tracy has to carry Ingrid Bergman about 30 feet (in a “threshold carry”), including up a short flight of stairs. Tracy had a bad back, and Bergman was slim, but she was also about 5’10. Bergman had to wear a harness, and if you look closely, you can see the wire holding her up.
This sounds sweet but it has a real potential to be the soiree of an entire lifetime of hurtful jokes. Or real hurt.
Assuming a man can carry a woman just because he is a man is, on its face, sexist and drips of presumptive stereotypes.
Might go.great.
Or, he might tear a hernia that not only stops intimacy for a few weeks but is an immediately weak area, prone to re-tearing for the rest of his life.
He’ll be the butt of family jokes. It’ll be humiliating.
And, of course, don’t assume he won’t just drop her as he struggles to carry her.
Why is it perfectly okay to make an entire series of assumptions based on his ownership of a penis, but if a man came in here making assumptions about a woman, he’d be banned??
We’re making the assumption based on the fact it’s a really short trip, the fact that there’s tons of evidence that a willing woman can be carried relatively easy for that short trip, and because we believe he has two arms.
But all that said, if he’s worried, he should try it first! Go to someplace without a ton of cameras, have her hop into his arms, and have him walk two steps.
If that ends with him in the hospital then by all means don’t do it in front of witnesses.
Are you sure that it’s her weight that’s the issue and not his height? Or her height and thus width when carried? (Depending upon how he carries her.) I’m sure he doesn’t want to crack her head open on the door. If she is carried such that she puts her arm around his shoulder then her head is going to be higher than his, and that’s going to be very close to the height of the doorway.
That’s what I was thinking. And we all know how sexy firemen are.
My wife is a Reubenesque woman, and always has been; she undoubtedly weighs more than I do.
When we were in the run-up to our wedding, she told me, more than once, and in no uncertain terms, that I was forbidden from attempting to carry her across any threshold. 
Beyond her concern for my own health, it turns out that she has a bit of a phobia about being lifted off her feet.
In movies and TV sets when a guy has to carry a woman there might also be wire-work involved that takes some of the weight off the guy - because some people have bad backs even though they look healthy, and because you don’t want to risk the guy getting hurt after multiple takes lead to muscles strain or worse. And yeah, the woman to be carried might also be tiny, sets adjusted to make it easier, and so forth.
>cough<
I suppose it depends on the broomstick… 
I’ve been picked up by guys who knew how to do it and everything was fine. I’ve also been picked up by guys who were weak/inexperienced/whatever and been dumped on my ass, usually with him underneath me. At this point, I’d prefer NOT to be picked up.
It’s very validating that you guys think so but actually we women often have rotten upper body strength, and probably can’t. My spouse is about 5kg lighter than me and I don’t think I could ever have honeymoon-carried him. And I’m not unfit - I cycle and swim most weeks, but I don’t do any targeted upper-body exercise
Piggyback, sure - that doesn’t require any arm strength. Wouldn’t be very romantic though. (“Aargh! Urrrgh.” stumble headthwack “sorry!” clomp clomp thud “aaaah…”)
Is it a big societal expectation to do this in the US? I’m seeing an awful lot less ‘well, they could just not bother’ than I was expecting here
It’s my impression that it’s part and parcel with the standard ‘traditional’ wedding - rice, flower girls, a big church building and a priest at the front. As people veer away from that I get the vibe that the grip of all wedding traditions has weakened similarly.
But what do I know? I haven’t been married enough times for it to be a statistically significant sample of american weddings.