Most Helpful Girl
No offense, but I honestly think it is highly stupid and simply going to cause one huge mess sooner or later.
1. Once you start dating other people and plan to pursue serious relationships with others, it will make things highly uncomfortable for the new people in your life. They may even feel slightly disrespected depending on how you guys behave while living together. If I was interested in romantically pursuing a guy and found out that he lives with his ex, I would be dismissive of him IMMEDIATELY. Sounds like one huge, complicated mess that will just bring me stress in the future. Many females cannot seem to get over their ex and some of them are outright tactless and borderline sleazy about trying to get him back. So you would probably see a case of some connivng jealous ex and a third party would just get hurt because of your tangled mess.
2. This will most likely lead to a friends with benefits situation which would be very unhealthy and foolish considering the fact that you two live together.
Honestly sounds like you're not ready to let go so you want to trap her into being around you by living with her. The whole idea is really stupid to be honest.
Most Helpful Guy
You have already listed plenty of reasons that things could go bad in this apartment partnership. Add that any future boyfriend/girlfriend that one of you starts seeing is likely to not accept their SO living with someone they have a sexual history with, even if there was not the current sexual tension. I could see that it could work for some people, but definitely does not look good for you two.