I am close friends with my ex girlfriend and we hang out, and are looking for a place to rent together. My partner loves her, is comfortable with the fact we are still close, hold love for one another and share a history. She even finds it admirable that I can be on such a great level with my ex, and harbour no ill feelings. Some people don’t work out as partners but can definitely remain close and in each others lives as friends. I can say for certain I don’t hold romantic/sexual feelings towards my ex and see her purely as my good mate now and my current partner respects this! Probably not what you’re wanting to hear but it’s definitely possible to remain friends without anything suspicious going on.