Mind to tell how many times did they have sex?

if only few times, then your friend is really being unfair to the guy.
unless they've been having sex for 50 times and the girl still feels hurt and uncomfortable, then she can be forgiven.

Perhaps the guy is still new to sex, and doesn't know the way or 'technique' to comfort the girl when having sex.

Practice makes perfect.

Undeniable, sex is very important, not just to guys, but to girls as well.

Your friend expects no sex for her husband after marriage?
She expects her husband only 'play' with his 'bestfriend' which is his hand for the rest of his life?
What if her husband go hunt for sex next time?
It will make things worse.

Both should enjoy sex.

The girl feels hurt and uncomfortable after sex.
Would it be some kinda problems in her vagina?
or the shape of penis of the guy is causing the girl feels hurt?

Should understand the problem why would it happen.

Some girls are like the vagina fluid is not enough.
The vagina is dry.
If intercourse sex occurred, of course it will feel hurt.

Try to be intimate with each others first.
Lighting is very important to gain intimacy.
Don't when feel like having sex, just undress and do it...