Say you saw a post from his ex on FB and it's worded funny as you think she's still referring to him as her fella. I'm assuming that's what's worrying you at any rate. If he's with you or your dad most of the time, then I would imagine there might be a good explanation. The ex could have a new boyfriend who has also just found work, it's not that unbelievable given the hard times lots of people are happing in the current climate. I just don't know what your other options are; well I do but it doesn't sound like you can just forget about it, and I'm guessing that snooping around on facebook doesn't sound particularly appealing. I just think a sensible conversation (it doesn't have to be a row) would probably give you more of an idea.