trust issues

i’ve been with my boyfriend for almost 2 years. i want to marry this man, and idk where id be without him. my trust issues are almost breaking this relationship. i’m trying really hard to get over it, but it feels like i start from scratch every time i get upset. he’s done some things in the past to make me lose my trust for him. we both are trying to be better. sometimes i feel like its not worth it. i really want this to work i am 100% dedicated. please comment advice on how to overcome trust issues