Not seeing each other for 20 days, is it gonna last?

[yo]

Relationship advise please??? I'll (try to) make this quick:

I'm 20 (girl,student) ,he's 26 and we've been together for a month. I'm very insecure with myself,which bothers him a lot, and he's very social with lots of friends and a good job.
While to me he's pretty much the only one I've got because I'm new in town. (I do my best to hide it but yeah) So I left to visit my family over Easter (in another country) and I'm very sceptical about our relationship. I mean,in the start I was convinced he was playing me because even when we got serious he kept liking other girls pictures on facebook and often checked other girls out when we went out together. I played very hard to get since I was very unsure about him and I think that's what made him stay. Though towards the end he saw my vulnerable side and I probably opened myself to much to him.
Anyways,the day I left he was generally in a happy mood (I was crying,I felt like an idiot) and since I arrived he has sent me like 2 messages on facebook asking if all's ok and stuff. The past month we have practically spent each day together. And especially in the beginning he would promise me the world : that he would buy me stuff, marry me (!) never hurt me etc. As I opened myself to him it seems like he got a bit bored, I don't know how to say,he stopped trying that hard. I have no idea what's happening. I should probably continue playing hard with him,but honestly I feel like he's going to cheat. :/