Why does ocd attack the things that matter most to us

Why is it that you beat one OCD think, but another OCD thing comes up related to it, but the same theme?

I hate myself a lot and don’t understand. I do so well for a few days then spiral and feel so awful bc it feels true. The BIGGEST and WORST trigger and theme has been my brother old friend ish who I had a crush on yrs ago. Since my ocd returned once I got in a relationship (after many yrs of being hidden) this theme is the most brutal. For some background I had a crush on my current boyfriend last year in February til May and we were friends then we started talking officially in end of May then dating in 2 week of June. I was obsessed w him 100%. The one time I even saw this old crush and the mall and my 1 friend and I followed him bc like old crush yk and I literally like stopped caring like idk how to explain it bc it was a while ago, but it didn’t matter to me. I eventually walked away and then later used that as an excuse to talk to my biggest crush (my current bf). Since we began dating, my ocd has been brutal. My little brother mentioned the old crush the one day saying “you still love him ur lying to urself rn by being w ur bf” and then it sent my mind on its first loop ab that guy. Since then, it’ll return getting worse and worse. (Sometimes I actually don’t care and it won’t feel as tru and ik it’s fake, but others it’s terrible) I hate it. And I feel so awful like I needa check to make sure I don’t like him. Yet logically why would I check my feelings. Ik I love my man bc everything ab him I love and he’s my comfort and best friend. But I get so stuck up in the confusion of all the thoughts ab this other guy and all I have wanted for the 10 months I’ve been dating my man is to go back to normal. Back to myself. The one who was head over heels obsessed w my man and completely forgetting ab the other ppl. But my brain says I can’t bc a part of me will always want the other guy or some other lame bs excuse and it hurts me so much and my man sometimes too. I’m considering medication but will it truly work? Will it make my thoughts go away? I hate how real/ true they feel I feel like a cheater or like I am lying to my man. I feel like rn when I say I love him, that I’m a liar😖for the past 3 days I was better. I gave it up and let God help me, but last night into today I’m lost. Are we sure ocd attacks wuts most important to us? Bc why is it so persistent and evil

my OCD is doing what it does best and it’s randomly selecting themes. Once I’m not scared or react to one it bounces to another. And then i temporarily forget all of my coping skills for that theme. Rn it’s fixating on the time I had a panic attack and it’s trying to make me have one again