How to overcome this hole i'm in?

How do I overcome my "Loneliness"?

Hi, quick context: couple years ago (8-10 years ago), I began to notice that I don't really fitted in my friend-groups in school. It's like I am cool with everybody, but I don't really feel "welcomed". I started to not let my anger out and keep it inside, which is why it started to build up like a "wall" around myself.

In addition to that I found a girl that I really like in University. She and myself are muslim, so we talked, that we are going to marry and not be in a relationship. We also said that we are going to first get our bachelor/master degrees and have a solid life foundation before going to the next step.

She was the one who created a little crack in this wall. But she started to be more distant and emotionally cold towards me. It felt like a pile of stones (which were my frustration and anger built up inside me) are falling down at same time

I made my happiness dependent on her, which was a fatal mistake (well we said, that we first start to build a solid foundation until we get to know each other, but I was so blinded by the affection which is why I made my feelings dependent of her).

Now I feel like im in hole, broken from her and the mixed feelings inside me. I have good friends and relatives around me, but this alone sadly doesn't help me. What advice would you guys give me in regard to this topic?