You are in a difficult situation
....I am not sure what year you are (a junior?), but he is a senior, so assuming that he is not going for a fifth year, you don't have much time left with him.....With that in mind, I would say go for it...but like the others said, don't be confrontational.....flirty and fun work
....but I would see (just subtly test the waters) ..... at least then you will know for sure......just be prepared....you have a point, maybe he does want to play the field or maybe he doesn't want to start another relationship because he is graduating....and it really is risky putting yourself out there.........but could you live with yourself if you don't see what is there? Good luck!!