Hey Rochelle,
Since you're already three years far in your relationship, i'd definitely try to talk to your partner about it. I've been together with my girlfriend for eight years now, and we're a great couple but it wasn't always like that and trust was a big factor.
We talked about it and basically, it came down to her asking me to help her trust me. And that's what i did. I told her i loved her every single day and that she was the one for me, and that i'd be foolish to give up what we have for whatever reason.
If you feel your partner is trustworthy and he really loves you, i doubt he'll have a problem with you asking this. By this i don't mean going up to him and asking him to do X and Y in order to achieve result Z, but talk to him about why you have such issues. A lot of couples are made up out of people that really love each other but are so afraid to lose their significant other to someone else, that the whole relationship goes to waste because of trust issues.
Don't let that happen to you. If you feel you both love each other, there's no reason to not talk about it and grow out of this feeling together. You'll both feel much better afterwards and your relationship will be stronger than ever before, so don't be afraid and go for it!
Feel free to pm or reply if there's anything i can help you with. Good luck and have faith!
