One night stands and sexual relationships in the gay world.

Hey guys, I am a young (20-25) gay guy, who is really frustrated about relationships in the gay world. I hope some one can help me try to understand and cope with this following problem. It is hard enough to find someone who is around my age, my type and a polite person. I am someone who rather likes to be in a relationship than just to hook up. But most guys at my age just look for hook-ups and change you as frequent as their underwear. Two scenarios that really frustrated me for example: I had one ONS with a guy (my age) that was nice, cute and my age. We went back to our hostel to have sex and as soon as he came, he didn't want to stay anymore and left. No goodbye, no hug, no kiss, no possibility to stay in touch. Just left. (He enjoyed it a lot though) The other ONS was with a guy (my age) that I met at a party, we talked, I kissed him and asked him to go back to my place. We had sex, as soon as he came he falls asleep and takes 2/3 of the bed. He wakes up at 9 am, puts on his clothes and leaves, with out really saying goodbye, no hug, no kiss. He accepted my fb request the same day, but that is all. I found him now on grindr again (on the same day)...... He leaves really close to me and is a foreign student. TL;DR Why does everyone behaves so differently the next morning? And for the second scenario: Shall I text him or wait till he texts me, and if he doesn't just let it go? Thank you, I am grateful for any advice.