And kudos. Combining lust and sloth (two of my favorite deadly sins) in a most amusing way. Now if only we could work gluttony into the mix we’d hit the trifecta.
What, are you George Costanza? 
OW! What’d I ever do to you? 
Anyway:
1) Have you experienced instances where you were unable to accommodate a lover completely?
Yes.
2) Painful? Unpleasantly so?
Had to stop and change positions - it felt like very bad menstrual cramps. This does not feel like pleasure. This is not a joyful time. Fun time is not being had by all. Will not love you long time if adjustments are not made.
3) How common is this in your experience (like, do you talk about it with your mums and girlfriends the way you do about feminine hygeine products?)
Never spoke of this to anyone except this message board and the ex with the giant ego/dick combo. He just assumed because he had a big dick he was just naturally good at sex, so anything he did would be great. He had *no idea * how to wield that weapon.
Bigger is NOT always better. Sex is no fun when you feel more like you’re negotiating a parking space (a little further… to the right… back up! back up! Okay… okay right there) than just flowing with the rhythm.
I told my husband I was like Goldilocks: The first boyfriend was too small (he was - not saying it out of spite. He was smaller than a tampon.) The second boyfriend was too big. Ouch.
But the third boyfriend was juuuuuuuust right! Married that one. 
A slight hijack:
I’ve seen videos of women using dildos that appear to be the size of a household fire extinguisher.
Are these women hollow? Guys, wouldn’t you hate to try and follow that act?
There are times when this happens with my husband. I had mainly attributed it to the fact that I am very short, and short-waisted, so I probably have a short vagina, too. It happens mainly when the positioning for sex involves my legs being hooked over his shoulders.
Yes. Yes. Painful as in “we must stop this now and change positions”.
I have no idea. I never can get anyone besides my husband and you people to talk about sex around me.
If that’s what it takes to beat you into a sex thread…!
Better than a catfight at a bargain bin.
We should sell tickets.
And to think I used to be shy about participating in sex threads.
Were these acquantances postpubertal?
:Dsorry…
I’ve run into this problem myself.
I’ve got nothing useful to add, I’m just bragging.
Just say no to crystal meth.
Well, if you’re lying on your back, she can’t complain about dropping crumbs on her…
It’s been my general experience that girth is more of a show-stopper than length. As one lady said, “If it don’t fit, don’t force it.”
We used to say fucking a girl like that was like standing in a doorway and fucking an empty room.
Or throwing a hot dog down a hallway.
But… but he’s… wah?
What are you getting at?
I’m (in the very clincal words of an ex-GF’s doctor) a ‘larger male’. I encounter this problem regularly.
It seems to be a combination of relative anatomical sizes, favorite positions and unfamiliarity betwen new partners. It is also much exacerbated for certain conditions (e.g., endometreosis).
Er…you do realize that sometime small human beings come out of those things? And yes we’re hollow for that very purpose .
It’s all about potential space not actual.
And anyway as far as the OP, it’s about depth not breathe.
And yeah bumping up against the cervix is a Very Bad Thing. Much like getting kneed in the balls. But while size is a factor I think it has more to do with ackwardness (no offense Inigo, if she was on top she has no one to blame but herself.)
Hot Dog! Just in under the wire!
So, watcha doin’ this weekend?
True, but how far can you go in before hitting something? This thing was huge!
I bet its not so much fucking an empty room; its probably more like accidentally falling down a flight of stairs