I didn’t have friends growing up, and it’s pretty hard for me to make friends because I’m not a “normal” person. Most people don’t know what to do with me. But after a few years in college, I made a few really good friends. They all went their way, as did I, but we can still consider each other as a good friend still.
I think it all matters on what you do and what you are expecting of others. Maybe you are looking at the wrong kind of people? Maybe you are expecting too much? Maybe you aren’t appreciating the people you are around for who they really are? Maybe you are putting too much pressure on others and yourself?
Also, this generation seems to be less willing to commit to hanging out because of the fear of missing out factor.
As for the girl, quite a lot are going to be like that. Not everyone can take things slow and wait forever, and not everyone has the same ideas for a relationship. Maybe you can look at what kinds of things you do while in a relationship. Are you rude sometimes? Make a lot of jokes that might be considered rude? Try to take over and control things? Maybe there was something that pushed others away.
Try to realize that what you do and how you think about it makes all the difference.