Fear of partner cheating with my sibling

I’ve been struggling with something that’s been really overwhelming, and I’m hoping to get some perspective from others here. I feel a lot of guilt about it, and I’m not sure if I’m alone in this experience. Lately, I’ve found myself daydreaming about romantic situations or getting caught up in ‘what if’ scenarios—where I wonder if I could develop feelings for someone else, or if someone develops feelings for me. The thing is, I’m in a relationship that I love, and I don’t want to act on these thoughts at all. What makes it even harder is that these thoughts often hyperfixate on one specific friend, and sometimes they feel entertaining or give me a dopamine rush. But then, of course, I feel even more guilty because it makes me feel like I’m betraying my boyfriend. These thoughts usually happen when I’m upset and looking for comfort, but then they morph into romantic scenarios, which makes me feel so disloyal. I’m constantly going back and forth between feeling curious or entertained by the thoughts and then feeling horrible for even allowing them to happen in the first place. I keep confessing these thoughts to my boyfriend, and he tries to be understanding. He’s just never been the type to daydream, so he doesn’t know if this is something other people experience or if it’s just me. I feel like such an awful girlfriend. Has anyone else dealt with something like this?

Hi, I'm 17,about to be 18. I've been struggling with these thoughts for the past 8 months. I was wondering if someone experienced ever the same because I feel im "different". BACKGROUND: (I'm not diagnosed with Ocd but seeing a local counselor) About 9 months ago I cheated on my boyfriend with this guy S (who blackmailed, manipulated and molested me). Since then when I realized that what i did was very WRONG and so I started ruminating picking apart every single interaction and telling my boyfriend, i tried to remember every single detail because otherwise I felt like i was being a fraud and hiding things to save myself, i had many crisis about it because I had also what i think was false memory ocd. My boyfriend forgave me idk how tbh I still wonder. CURRENT STRUGGLE: Months ago I was sure I didn't wanna S in any way and i was sure even when everything happened. For the past 2 months tho I've been having thoughts like " Do I love S?" "I love S" "S is hot" "Would S find me hot?" "What if I want S?" " What if I don't love my boyfriend enough?" "What if I secretly want S?" "What if I see my boyfriend as a friend only?Do I?" And I tried testing my reaction to intimate scenarios with S, I'm scared I like it i dont really wanna love S or have any secret attraction, I wish I didn't have any of this and I want to be sure of my feelings for my boyfriend because I know I wanna be with him and I see a future with him like he brings me comfort. But a part of me keeps trying to convince me otherwise. Sometimes I think I'd rather die than have these thoughts. Im so scared of not being able to control my feelings, im scared I can't resist S and its giving me anxiety and making me cry. Sometimes when i think of those sexual scenarios with S or I get those thoughts my mind tells me to smile because i like it because I find it funny. It makes me doubt myself all over again. Like I'm always like I need to test if I'd feel aroused to intimate scenarios with S, lately im trying to fight this urge to test and test but my mind is like "just do it this once so you can be sure. I can never watch anything romantic or sexual or whatever because my mind would be like "you and S" or sometimes I'm just enjoying time with my bf and im like " yes we can just have a sneaky cheating thing thats ok" and it makes me want to figure it out to find an answer a solution because idk it just does like I need to find the meaning of it if it means the truth and all. Im worried im just an awful person and these thoughts just ruin my quality of life . Today i had a crisis where i ended up doinf swlf harm, I'm so scared of finding someone that's not my boyfriend desirable or sexual appealing or whatever it is, I also have bodily reactions when I try to imagine and test my reaction to scenarios. Now i keep groing everytime and I dont know why but i have this sensation and I dont want to havebit especially when its something S related. Does someone experience the same thoughts? Am I alone in this? Is this ROCD? What should i do?

my spouse cheated on me on our wedding night and i haven't gotten over it. they never told their parents and i was resentful their parents didn't know. so i called them and told them today. it felt good in the moment to have that extra support from my in-laws but im freaking out now that i have to confess to my partner and they will feel betrayed by me and leave me. is this confession OCD or a real fear? i'm really freaking out.