Stuck on relationship

I’m dating a guy that has a different partner and I have all sorts of emotions attached to it, starting with shame.
His partner’s other partner doesn’t know about our relationship. I tried working on a model, but I don’t know if I created this new thought to justify myself.

I do believe that there are different kinds of relationships and there is no “right” answer to it, but I also feel like maybe I’m hanging on to this new thought just to make myself feel better. Where do I draw the line? Any advice on this and whether I’m doing the model correctly would be helpful. Thank you!

C: Dating a guy that has another partner
T: I shouldn’t be doing this
F: shame
A: being secretive about it, not talking to people, constantly questioning whether I should be in this relationship or not,
R: Hiding and finding evidence that I shouldn’t be doing this

C: Dating a guy that has another partner
T: It’s okay to have different forms of relationships
F: calm
A: try to look at the good things about the relationship, try to learn from the experience, try to get to know him more
R: Try and deepen the relationship