Why can't some people just ever find good people to be surrounded by?

I put in so much work and effort and I try being loyal and present for the people I befriend. But they just end up taking and leaving. At this point I feel like I'm just a bridge for people to get over. I just want to be cared for the same way. Today I just wanted to do nothing and cry and cry and cry. I feel so alone. I'm going to be 30 this year. And still alone. I'm so tired of life.