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

I'm struggling really hard with relationship obsessions. Do I really love my partner? How can I know? Am I really just faking it? That kind of thing. It's making my life and relationship a lot harder than they need to be. I could use a few helpful coping mechanisms, trying to move away from less helpful ones like chasing reassurance.

When my boyfriend and I are apart, it honestly feels like I've lost all feelings for him. I start questioning everything, wondering if I even love him at all. Then, when we're finally together again, the memory of those earlier doubts creeps in and completely ruins the moment. I get so caught up in overthinking and analyzing my feelings that I can't even enjoy being with him. It's like I'm constantly second-guessing myself. The worst part is, sometimes later, when we're still together, I do feel the love. But then the anxiety kicks in again! I start worrying that I'm just faking it because I had those doubts earlier in the day. It's this endless cycle of questioning, doubting, and overthinking, and it's exhausting. I'm really struggling to stay present when we're together, and it feels like this constant cycle is preventing me from truly connecting with him. We have been together for three years and we love together, and I just started feeling this way about a month ago; it’s been almost every day since. One day, I randomly thought about breaking up with him. Our relationship is healthy, especially compared to my previous toxic one, where I was anxiously attached for two and a half years. My boyfriend is very supportive of me. I have talked to him about my doubts and everything I’m experiencing, and he continues to support, care for, and help me through it all. I am very grateful for that. One aspect of my current relationship that I would like to improve is our communication, but we are both willing to work on it together. I often find that my overthinking leads me to question whether I really want to try to fix things or if I’d rather just continue as we are. This creates a constant push and pull in our relationship. Has anyone else experienced something similar? Any advice on how to break this cycle and just be present in the moment? I'd love to hear from anyone who's been through something like this.

I'm 18, and been in a relationship with my man for nearly 2 years. I started living with him around 2 months ago, and all I do is think about if he's cheating. We were long distance for a year and a half of our relationship, maybe seeing eachother once every month or two. I decided to move in with him, and ever since all I can think about is if he's cheating or watching porn. When he's in another room I think he's doing something wrong, I have to check on him every ten minutes to ease my anxiety. I didn't have this problem before moving in. Granted he has talked to some girls on his phone, even having his ex on his phone (didn't do anything bad) and he is porn addicted though he is getting better for me. It's gotten so bad I want to leave him. A couple days ago I broke up with him and it absolutely broke my heart, I couldn't bare it so I gave him a month to show me he can do better, and for me to work on myself. If I'm still unhappy with us I'm going to leave. I love this boy more than anything. I'm scared to be without him, this is my first real relationship. At this point I refuse to even sleep until he is sleeping. I don't want to start over, I don't want to leave him, but I really can't take this pain it's causing me. It's all I think about. I've convinced myself so many times that he's cheating, but I know he wouldn't. I question whether it's anxiety or intuition. Maybe I just know deep down he really is cheating and I just don't want to believe it. I don't know. I don't think he would do that, but at the same time he's really into women. I hate that he looks at other girls in a sexual way, it bothers me so much, and we talk about it often, but with it being an addiction it's difficult. He has gotten a lot better since we have talked about it. He understands I have an issue and is usually happy to talk about it over and over and promise me over and over that he's not cheating. He allows me to have his phone whenever I want and everything, I have no reason to think he's cheating, but I can't get over it. It's not fair to him either. How do I deal with this? How do I stop hurting so much?