Search Results: too much teasing

I met this guy about a month ago give or take. We've gotten a lot closer, and I've started to really like him. He's super sweet and athletic, not to mention good looking. We seem to really click especially in our sense of humor and interests. We tease each other a lot, make sarcastic jokes, and we talk more than should be socially acceptable. I got led on to this crush knowing I'd continue seeing him on a regular basis and I didn't think much of it. However, he recently told me he has something going on that would mean he leaves on Thursday in 2 days and comes back 5 months later. I suddenly feel sad, clingy, and sort of desperate. I don't know of he's single, and I don't think he likes me back. He's way too out of my league to ever like me back. I will really miss him, and I think he knows that because I sort of made it clear. I'm like 70% sure he knows I like him too. What should I do? Anything? Should I tell him anything before he leaves? Please elaborate too.