In love and so scared!

So, I've been dating my boyfriend for about 5 months now (nearly 6) and this is my longest relationship! I'm nearly 18 myself and he's 21. His last relationship was like 3 years and he had done the whole New Years, Valentine's Day thing etc. We spent New Years together but I didn't see him until it turned midnight because he was talking to his friends, he said he was sorry and told me how much he wanted to be with me all night, but couldn't get away. Which I totally forgave him for and got over it. 
But now Valentine's Day is coming and he doesn't want to do anything for it! I'm buying him football tickets to see his favourite football team play, but I'm worried he's not going to want to do anything with me. This is my first Valentine's Day and I'm scared he doesn't want to spend it with me. Also, recently he's been very sad and I dunno I feel as though he's distant, every time I talk to him he doesn't say much about it. But I got out of him last night that he's scared of losing me. I'm off to uni in September as well and he "jokingly" said that he was going to get a new girlfriend come September and that also scares me :( I'm scared he's going to leave me