You should try to find out what it is that is going on. If you feel someone is hiding something from you, confront them about it and ask for the truth. But, don't go looking for something you aren't sure you want to know.
there's one way to find out for certain, but, it takes a lot of patience. just sit back and keep your eyes and ears open. find out what you can when you can, but keep it quiet until you know for sure. i have the feeling that you already know but are keeping yourself to a rigorous standard of proof because you wish it wasn't what it is. i wish the best for you no matter what this turns out to be.