We have a rule that if our kids have visitors in their room, their door must remain open

Earlier today, my wife called me telling me that I needed to come home as soon as possible as she caught our oldest daughter giving her B-F oral sex.  She went into the room and said that they needed to get dressed and that wasn't allowed in our house.

My wife believes the issue is resolved and was angry when I told them I'd call his sister if this stuff continued.

We're giving mixed messages here in our parenting.  She's on the pill to regulate her period.  My wife found a vape pen (with THC) in our daughter's room a few weeks back.  The punishment was taking away the vape pen and getting her on anti-depressants.

She wouldn't ground her, let the BF's family know that we just realized they got high in her room 2 days prior. 

As a parent, you have to trust your gut but at the same point, you need to have a solid foundation to protect your children.  My wife says if we ground her or restrict them being together for a week, that we're bad parents.  I told my wife that they should only be in the living room or kitchen rather than her bedroom.  My wife says that by doing that, we'll cause resentment.  My wife may be okay if they perform oral as long as they are not having sex.  I'm sorry but they likely have already had sex, even if they haven't, they're sexually active and them having sex could happen any day soon.

It's not like I want to say, "Hey it's okay to have sex here as long as you're having it responsibly." However, I don't want to get a phone call or find out that they're having sex in public either.

What's the right solution?