The Sticky Situation

I met a girl in a pub one day on the way back from work. We got chatting, went on a couple of dates and ended up round my house. I woke up in the morning and she'd left the house without my housemate finding out. He's a heavy sleeper and works nights, so he'd gotten and gone to bed a few hours before she left. She goes into the sitting room first and immediately turns around and runs upstairs. Turns out after a bit of interrogation, she's been inviting my housemate round to her house for exactly the same thing. That she's coming round my house for. But we're still best mates and neither of us are seeing her.