If something feels off with someone, you don’t need proof to keep a little distance.

A sense that something is wrong is usually built from things you noticed without cataloguing, which means you often cannot produce an argument for it. You do not owe anybody a case. Keeping some distance is not an accusation and it does not require you to decide the person is bad. It only requires you to stop handing over access.

Let the feeling set the pace rather than your reasoning about fairness. Be a bit less available, share a bit less, stay in groups. If the feeling turns out to be wrong, you have lost almost nothing, and if it is right you will be glad you were slow.