Is it normal to deep down feel like you're being fooled by your so?

They say to trust your gut, but I tend to go over things carefully and clearly to finally make a decision so yes I ignore my instincts for a while. Especially when it comes to my relationship. I look at it without considering my feelings like a book I am reading, and everything looks right, things are going smoothly. But then as soon as I close the book, that feeling of doubt comes alive again and I can't go through my day. We didn't just jump into a relationship right away considering a lot of factors then, but slowly we dated and became seriously. But throughout us dating, so that includes not being exclusive, there were a lot of bad things that made me feel like a fool and it just hurt. Eventually, I look through his phone and found out he was lying to me about a few things. Yes he found out, wasn't happy about it, but although, we BOTH were not innocent back then, we're here now and better so it just meant we were willing to fix the problems and move on cause we did wanted to be together. Now that we're doing well, I just still have that gut feeling of being fooled but then I look at him and see a good guy, I look at our relationship, nothing toxic, but it's just this feeling and it sometimes makes me cry like wow be ready to be completely heartbroken. I don't know if I'm being in denial of the truth (what I feel) or my head might make up scenarios and I should avoid it. But it isn't my head, it's my feelings and you can't control how you feel. I do want to check his phone next time I see him for a peace of mind and have him understand that he betrayed my trust last time so I'' always feel this insecurity.