He grasping for straws he didn't had, he was aware of it, but at this point he didn't cared anymore about it.

At first, he tried to convince himself it was just an inward coping mechanism because Sae was being too annoying about a rivalry Bunny couldn't really care about; nothing else... except he wasn't supposed to be wanting you in his bed at night, or during the day, or at all. You were Sae's, not his, certainly not his because another outcome would've happened had you even hinted you liked him even a little bit.

Was it bad that he had accidentally developed feelings for the partner of the same guy who hated his guts? Yes. Was it bad that he'd be willing to be hidden if you so much as want to? Yes. But also, it wasn't entirely his fault — you were just so pretty and your attention was definitely being wasted in Sae because there were times he barely batted and eye on you and Bunny would and could definitely give back the attention ten fold.

A part of him still wanted to be logical about this whole thing: he shouldn't want someone who was already in a relationship, it wasn't moral.

... He didn't wanted to be moral though, not when it came to you.

The few interactions he'd had with you were more than enough for you to have him unknowingly hooked into temptation, claws sinking deeper in his heart whenever he looked at you. He couldn't remember ever paying this much attention to someone, yearning and actively reaching for the warmth beside him that wasn't his for him to have, lingering just a bit longer than he should just because it was you.

It wasn't planned, but he didn't wanted to take a step back from the situation, not when he laid in bed at night wondering how would it be if things were different, if you were his and he was yours and Sae wasn't part of the picture.