I need help with this relationship?

You don't explain why you believe it's okay for you and your boyfriend to have , but not Abby and her boyfriend. You may be trying to control a situation that doesn't require your intervention. Sounds like the 3 of you need to sit down and come up with some ground rules (Yes, even for you.) that you can all agree on. You may not want to face it, but she is getting older and doing something that is pretty normal for her age. Good luck.