When you are 48 you will be wishing you spent that time fucking more 18 year olds.
Well done. 9.3 from the Polish judge. 
OP, I think the reason most people have a problem with big age gaps in relationships such as this one is:
- the potential for power imbalances (one makes more $$, usually, or has a high-status position)
and/or - the fact that the two individuals are by definition at different stages of their lives - healthwise, careerwise … every aspect of their lives, really - can make it seem to others like it would be difficult for them to relate to each other
If these aren’t a problem at the moment, then … have fun! Enjoy! Don’t knock her up!
Eh, both of them are getting laid, probably frequently. As long as neither gets crazy about it, I see this as a short-term mutually beneficial relationship. Enjoy it while it lasts and learn what you can.
I really don’t see anything wrong with the situation…
as long as…
you can keep up with her.
>snerk<
Really? Most of the guys I know in that age group who were fortunate enough to be getting laid regularly when they were 18, by somebody they really liked and got along well with, aren’t spending any of their time nowadays wishing for a do-over. Why trash your own happy memories just because you’ve retroactively decided that what made you happy back then actually wasn’t good enough for you?
Yeesh. I can see where most 18-year-old guys wouldn’t be attracted to a woman 30 years older. I can see where most 48-year-old women wouldn’t be interested in a guy 30 years younger. I can see where an insecure 18-year-old might get somewhat unwillingly entangled in a relationship with a messed-up exploitative cougar and feel uneasy about it and wish later that he hadn’t done it.
But in the rare case that an 18-year-old guy and a 48-year-old woman genuinely like each other and have an enjoyable consensual casual relationship, and there are no indications that any hearts are going to be broken or any bunnies boiled due to unrealistic expectations or just general instability, then why on earth should either of them regret it farther down the line?
Has a waitress, bartender, etc referred to her as “your mom” yet?
Or “your grandma”?
Where did you two meat?
If she gives you a gold cigarette case engraved “Mad About The Boy”, watch out.
“They don’t yell, they don’t tell, and they’re grateful as hell…”
Not Heinlein’s idea. The Oneida Colony was doing that in the mid-19th century.
That should be can’t imagine, not can. I didn’t see that error when I was posting from my phone earlier.
All this snark and I can’t think of a single funny line. 
MsWhatsit won it early, though - everybody else is shooting for second place.
Whoever it was ripped off the idea from the real life Oneida community. The idea was that by having their first sexual experiences with post-menopausal women, the young men would learn how to control their ejaculation well enough so that when they were to start having sex with fertile women they would be able to avoid pregnancy.
It’s obvious that this kind of relationship is very unlikely to work out as a long term thing (and it really shouldn’t - honestly I think 95% of people should NOT marry the person they date at age 18).
But you know what’s worse than an 18 year old boy having sex with a 48 year old? An 18 year old boy having sex with an 18 year old girl who isn’t smart enough to use contraception. 
I bet there are a lot of guys out there who became dads earlier than they wanted to who wish they had thought of going after the post-menopausal crowd.
Y’know, I find I’m already over it.
And when you get a little older, there’s a chance, you will too.
Until that time, enjoy the ride. The same advice I’d give you if you were dating an 18yr old!
If it makes you feel any better, her friends are probably even more disgusted.
Telling people IS what this is about for him. And the woman deserves an immature response when tangling with an 18 year old.
I have yet to ever meet a teen that doesn’t think they are “mature their age” or exceptional.
Even if they really are mature, they are still simply mature for being 18. It’s hard to be “mature” when you live at home, etc.
I thought there was a “they don’t swell” in there too. That’s a rather big plus.
A lot of young people who think they are mature for their age are often wrong about this. They may be a little different and non-conformist, but that’s not necessarily a sign of maturity.
But even if you are right, chances are you’re no more than five years ahead of your time, not anywhere close to 30. Unless you are the reincarnation of someone. And if you do find that you have a lot in common, that means she’s probably a little immature herself. That’s not a crime, mind you. But it’s just something to remember when the honeymoon is over.
All that said, while it IS weird and your friends’ reactions are normal, that doesn’t mean you don’t have the right to your lovin’. You’re not going to get your friends to change (seriously, think about it. Will you feel comfortable bringing your lady to parties and social events? What 18-year-old boy wants to hang out with their friend’s “hot mama” and watch them smooching all evening?) So you may have to take a vacation from your peer group if you want some peace. They aren’t gonna be able to understand this, and it’s unreasonable for you to expect them to change.