Considering what the writers are trying for it was probably like on TV shows and movies. You know, two characters making out. "We need to stop" "Yeah, we (insert reason not to have sex)" Begin heading for bedroom alternately kissing, making excuses. Start pulling off each other's clothes, excuses beginning to be replaced by justifications. Fall into bed and say the hell with it.
"I promise not to look" would probably have been the last thing Black Cat said before they reached the bed.