Mixed signals, is he interested? Should I wait?

I met a really great guy at a University ball. We hit it off, kissed and exchanged details. He called me the next day and we went on a date the following Friday. The date went really well, and we both had a great time. Unfortunately he was leaving for an overseas holiday just a few days later. We spoke everyday up until he left, even made plans to catch up when he got back. I have heard from him but I've also seen photos of him kissing another girl whilst away (not a big deal usually, its expected of young people on holiday) but it seems like they've been spending alot of time together and she posted on his fb, saying she "liked him". I feel like an idiot.. I guess I'm wondering why he'd take me on a date if he knew he had a big holiday coming up? And if I should wait for him or forget him now because he may have moved on? I know I didn't know him well but I did feel something. I'm embarrassed and really confused. Help?