I feel like I'm ruining my relationship...help!

I've been with my SO for almost a year. I'm his first real relationship, and I've been hurt in the past. I love him so much, and we're expecting a child and we live together. I've been betrayed so many times and lied to that I feel like my paranoia could ruin this. It feels like it's too good to be true, he treats me like a queen. He gets me food when I'm tired, takes care of me when I'm sick, writes me love letters, tells me he loves me several times a day, helps me with whatever I need, let's me use his phone, goes with me to all doctors appointments, helps me pick out clothes when I go shopping, watches movies with me that he doesn't like, holds doors open for me, holds my bag, etc. I love him so much and he always reassures me that he doesn't want anyone else and he's gunna love me until we get old but because of the past I have this worry a lot that what if he's going behind my back or he's gunna cheat on me or leave...advice? I feel terrible for feeling this way and I just wanna be able to not have to worry about this so I can enjoy it 100%