Why do guys show an interest in me then suddenly reject me?

Over the last year, I just happen to meet guys who seem really cool, we get on like a house on fire, they are really keen and want to chase me, send me a message or two then just stop or reject me altogether! I like to take time to know a guy in that way and many have told me they find me easy to talk to. I am at a point in my life where I would like to find a guy and settle but I am easy going and certainly don't push that kind of issue onto them. What am I doing wrong? I start a date feeling great then end up feeling like I've been whisked through some sort of dating conveyor belt! I want to remain positive but I'm starting to feel pretty crappy about it :(
Updates
+1 y
Thank you very much for all your comments, I really appreciate the advice. After reading through then pondering over everything, I feel that I definitely haven't met the right guy yet so am currently enjoying my singledom :)
Why do guys show an interest in me then suddenly reject me?
Post Opinion