I've been with my girlfriend for 5 going on 6 years. I'm very insecure when it comes to anything. Whether it be physical appearance or even people stepping in and taking my place in her life.
I don't have many friends at all. Maybe like 5 and like 3 that I would hang out with. She has a group of friends that she's constantly with. I always feel like I'm missing out on something and I feel like she would rather be with them than me or that they're more fun than me.

It causes so many issues and I start arguments saying how she thinks I'm not good enough and it's ruining everything.

I'm so tired of being insecure about everything and I feel like I have tried so many times to stop it but I can't. It'll be better for a little bit, but then it always comes back. I'm so close to losing her and I can't have that happen.

Any advice at all would be helpful.
Thanks in advance!