How does one become more grateful towards their partner?

I was emotionally abused by a close friend for many years and it has caused some pretty intense emotional scars. I am now finding it hard to be grateful and loving towards my loving and amazing boyfriend of almost 2 years. I love him so much and he treats me like an absolute princess and is so supportive of everything I do. He knows about my past and everything. But lately I’m having a hard time letting him in and being grateful for everything he does for me and I am feeling so guilty about it. But in the moment my irritation and insecurities take over and I can’t just say thank you. I have to get upset over something. I can’t keep hurting him like this even though he says he’s fine it is straining our relationship. Please if anyone has advice I am all ears.