Sounds like you have good grounds upon which to be suspicious. The bottome line is that from what you tell us... it looks like there is a bit more going on than just buddies. Maybe inviting them both over to your house and seeing how she treats you would be a good idea, you'd get to see if she would have much to do with you while he's around. If she hovers around him the whole time it would say a whole lot about where her feelings lie.

I'm not very good at this stuff though. Just hope you can work things out. Good luck.