Why do I think about my death and sadness

I believe I’m paradoxical because I love my gf with all my heart but I fear to show it because I’m afraid I’ll scare her. I live a normal life but all I can think of is my sadness despite the good. I wish for my death but I try to hope that it will get better I am afraid of being with people for them seeing me and what I am, because I feel like I lost friends that I didn’t even make. I look for hope and happiness, but why do I just focus on the bad. I overthink every time by girlfriend has, every expression because all I want is to make her happy but at the same time I believe her happiness is without me. I’m afraid to be happy because I feel like I’ll hurt people if I’m happy, I want to make people happy at my expense because if I could make them happy I feel like I’ve done good. But I don’t want people to sacrifice things they want to do, for me like I do for people I’m confused and scared of getting it wrong, I don’t care who responds at this, I don’t judge and I love you all the same

Who am I to judge another man if I too walk imperfect

If you could just give some advice no matter how old I just want to know

-thank you