Anyone having unnecessary and excessive doubts on their girlfriend/wife or boyfriend/husband being unfaithful to them?

does anyone have any tips to help with hyper vigilance in a relationship? In my past relationship I got cheated on and it hurt me mentally, and now with my current partner I always have a constant fear that something bad is going to happen even though I trust him a bunch. Like if he brings up another girl and says oh she said this. And I get so triggered by it, how do I stop. Like I trust him 100% but my mind isn’t letting me, and I feel like I always start this and do this to myself. Or if it’s a girl from his past relationship and something gets brought up about it because of me, and he’s tells me it still makes me mad.

For about a month now I’ve been really obsessed with the idea that my girlfriend has feelings for this guy we know if he has feelings for her. We’ve only known him for about a month and we’re not that close to him. The stuff that makes me worried is completely normal for friends to do or are things that aren’t real. . They respond to each other on group chats . They hangout in groups when I’m not there . She finds him funny and smiles when she’s around him . I just have a bad feeling It’s become such a thing in my mind and it’s deteriorating our relationship. Every time I see him and her talk I feel mad and sick and anxious. And now I’m starting to hate him. I feel like I’m being so unfair because she hasn’t actually done anything, and I keep accusing her and treating her like she has. She says she feels like all I see is the worst in her and like she’s a bad person. I’ve brought this up to her many times and every time she tells me she would never cheat on me and that he’s some random guy and that she doesn’t want him she wants me. I just can’t get the idea out of my head, I can’t stop unconsciously looking for signs of romantic feelings between them. I analyse her body language or how she looks at him, I check if there online at the same time to see if their texting or something. It’s really bad. It’s gotten to the point where it’s not about the idea that they have feeings anymore it’s more just I want to get the idea out my head. I want to stop seeing this. Because she would have said something by now. And I know this is coming from a place of fear and insecurity about myself and the way she feels about me, because he’s no different to any of her other friends I just chose him to be the one I worry about. I want to get past this because our relationship needs to move past this and I want to be able to enjoy the time I spend with my friends instead of relating it to this and the idea of hanging out in this group with her where he is, and if causing instant anxiety. She’s not like this, she’s a good person. It’s not necessarily the idea she’ll actually cheat it’s the idea she’ll develop feeling or he will and will make her catch feelings too. It’s all just a “bad feeling” I have and an obsession with this idea. I can’t stand to be around them in a group cuz all I can see is that “she’s in love with him” or “he would make her or does make her happier”

I suffer with a constant worry of what if I’ve cheated. You name it I’ve thought I’ve done it. I’m quite flirty at nature and also insecure. Sometimes hand in hand I don’t think they balance each other out as the constant need for attention to validate myself can backfire. Although I have the best partner ever and she makes me feel nothing less than beautiful I still crave validation from others. That being said someone I used to work with left over half a year ago and when they worked at my current place of work we were very close. Text everyday, phone calls you name it. However looking back I was extra flirty as I wanted him to fancy me. I wanted the power to turn him down to make myself feel better. Awful I know. Now all I can think about is what if I’ve done something. What if I kissed him. What if I’ve slept with him etc. I’ve kept our whole conversations from the minute I got his personal number. I constantly search key words to see if my intrusive thoughts are real. I can except the uncertainty my therapist tells me about as if I have done the worst and cheated I would loose my partner and our 10 year relationship. I love her so much she is my life but I can’t stop thinking what if I’ve cheated. Does anyone else suffer with the same theme? If so how do you cope?