How to deal with rejection?

So, i talk to people, and at first they seem to be good enough till i developed some liking towards the guy, and then suddenly they just stopes talking...i don't think it's me, but i don't have enough courage to ask anyone that, what happened, i feel that there is something holding me back, that if he wants to then he would talk to me, Right? There a a few people I have had conversation and i liked them, but why guys do that. This is the biggest question in my head and does this happen to others as well? I just feel a bit awkward, infact there are people who would say let's have a call, and after talking to then once or twice, they just vanish. Now it can't happen with everyone of them and there are some people who just don't stop talking, and i feel that noo, i can't deal with people who just too dependent ( i mean emotionally)i mean how do I deal with this and what should I think? Or should I text take any initiatives?? This is so confusing or do I need to see a doctor? Pls suggest if any one have anything or have faced similar kind of things