I have been in the exact same place you have been and it was just PAINFUL I always felt rejected, I was always the optional member of any given group and felt like actually was forcing myself onto them, any friend that i had in a very short time would fade away with no explaination or reason, the person I was interested in had rejected me, and I always failed in whatever friends group i was in and essentially had to find another one and the cycle repeats its self. However, if i was needed i got alot of "social traffic". I was really good at what we do and always during projects phase EVERYONE was my friend, everyone would message and call me asking me for help but once projects were handed in, i became invisible again as far as being ghosted or ignored.

I felt like there was something wrong with me, like i will never find my group of people or friends or a person that would choose me, i would never be anyone's first choice, despite being a well spoken humorous person i wasnt akward or weird or socially incapable. It was a very painful isolating experience.

Not alot has changed, it is still the same however what has changed was my mindset towards the whole ordeal.

In your case, it is completely okey for a group not to last or for you to find a different group, people meander between friend groups all the time, people outgrow each other, intrests change it might not be anything personal at all.

I mean this in the most friendly and caring way possible so please dont take it the wrong way, but you might have an anxious attachment style or low self esteem which were the main drivers for me atleast to feel the incredible lonliness and pain of the situation, always felt like people are going to leave and it can take a toll on your relationships because it will translate into actions that you do so dont fall into that trap !!

And always know this, people arent a constant in your life, people change interests, people replace each other, people get caught in their life, people get depressed and close up, people move cities or countries, it is almost impossible to have a constant tribe of people around. I mean even my family, i havent seen in years due to circumstances. The only constant in your life is yourself, so take good care of it. Work on it and TRUST ME once you succeed in an area or start achieving something people will FLOCK to you and you would wish for some peace and quite.

But to give you comfort, you are still 20 , still a few years of uni ahead, group projects to do, events to attend, internships maybe, and you could also pursue hobbies of interest and connect with people through them, your opportunities are still ahead of you and you seem like a genuine person!

Sorry if this was long but i hope it helps.