Yes, you leave.

You bid farewell to her as you get back into your clothes. Leaving Belle playing with herself on the bed as you leave the room. You make your way to the door and leave the house, pulling the door closed behind you. The doors lock catching as the door properly closes. You enter your car and just as you're about to start the engine you realise that you've forgotten your wallet. It must have fallen out of your pocket when you took off your trousers. You weren't really focusing on taking them off so it's not too surprising.
However, since you've now left the house and you automatically closed the door behind you, remembering the door locking. To go back in now would be almost a little awkward. You can do without your wallet for a few days you're sure. Either you'll pick it up in a few days or Belle can drop it round for you. Might be a good excuse for another round...
With that you shoot her a quick text about your wallet and then drive off back to your own home.
You don't see her responding text till you're back at home, you were driving. But you heard the ding when it came in letting you know that she replied near instantly:
"Sure, I'll bring it to you tomorrow, my stud ;) xxx". Maybe you'll be able to get another go at her even sooner than you expected.