My Insecurity is Destroying My Life+Relationship

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!

First of all seeing a therapist tends to help with this type of thing. Also joining a group or club if you can. I gained a lot of self confidence when I took up a sport. My last therapist was also a fan of "fake it till you make it". Can you pretend to be self confident until you feel it?

I’m willing to try anything at this point. Maybe faking it can help and eventually I will feel and believe it. I joined a sport recently and have noticed I feel a bit better. So hopefully the combination of the two will help. Thank you so much!

That sounds really tough. I'm very similar to you I think, except neither my boyfriend or I have any friends really at the moment. I know I would feel insecure too. Anyway, it sounds like this is something you bring up with her a lot, and you likely have arguments because you feel threatened and as if you need to protect yourself. I wonder if you could approach a new conversation from a problem-solving stance and tell her you want to work on your insecurity together, but that it might be helpful first for you to hear in her words what she loves about you. Maybe you're not sure what she sees in you? I'm wondering if just hearing that will give you something to hold onto to remind yourself of when you're having a rough time.

Also, then you can practice taking your fears and really digging deep and analyzing whether there is evidence to support them, or evidence against them. It can be a very vulnerable and painful feeling to take a leap of faith and trust in someone's love for you. Another idea I have is to have a conversation about what you need from her to feel loved. Is it words of affection? Physical touch? Quality time together? It might be helpful if she shows the particular kind of love that you need.