I see that it is extremely difficult to have invested in relationships that haven't been as rewarding for you.
Speaking from prior experiences and my own trouble with making friends, i'd like to ask you to explore a few things that maybe worth looking at rather than make suggestions, promising to directly solve the issue at hand.
The way i see it, more often than not we lack control over the problems we have, but what we do have is the power to change how we perceive them.
For the longest time i was stuck in the ideal expectation of having that one best friend or one confidant that i could always rely on and more often than not i was constantly disappointed.
Instead i've tried to set realistic expectations for myself and the people around me and take things as they are. Over time, i've deeply appreciated the things each person in my life has to offer, instead of expecting one person to play the role of all of them.
What i sense here is more than your ability to connect with the people around you, which i think you're more than able to do, i see this as a slow learning process of how we are all in some ways, essentially alone despite being connected to the people around us. It can be a very strong and scary feeling.