Daughter (17) wants to stay the night at her boyfriend's (18) house after prom. My wife and I are in disagreement, what are your thoughts?

In our kids' teen years my wife and I are discovering that we were raised quite differently and we have pretty different views about how to handle situations like this (what is or isn't appropriate for our kids as they start dating).

Our daughter is a junior and her boyfriend is a senior. We live 10 minutes from the prom afterparty and there will not be alcohol involved (so no reason she can't just drive home).

I was raised in a Catholic home and went to Catholic school, and while I'm no longer practicing the faith those values (abstinence/chastity) still have some hold on me. I know they are sexually active and she is on bc but I will not condone their sexual activity. I think that teenagers have enough to learn about themselves and what they want from a SO/relationship without involving sex. Not to mention that neither of them are remotely prepared to raise a family and neither my wife nor I have any interest in raising their kids.

My wife was raised in a much more lenient household and was apparently allowed to have sleepovers with her SO while still in high school. She thinks this is no big deal and made the argument that we know they are having sex already, so what's the problem.

Allowing them to stay together overnight has come up before when our daughter has tried to invite her boyfriend along for multi-day family trips. My wife and I are basically at a point where any conversation in this area leads to a multi-day argument.

I will be talking this over with our marriage counselor tomorrow but I guess I wanted to feel out how would you react to this situation? And/or do you have any advice for how I can resolve this conflict with my wife? I'm feeling pretty stuck, thanks in advance.