we've talked about jealous eddie, and pining eddie, and afraid-he's-actually-a-homophobe eddie, but i think there's another element we need to explore and that's supportive eddie. because here's eddie diaz having just found out that the reason his best friend has been so weird lately is that he's going through this major revelation and it's all new and he's so excited and a little nervous, and buck needs his best friend to have his back as he explores these new feelings.
and eddie genuinely likes tommy, he was the one who wanted them to get on well! so even if it makes his chest tighten to see them brushing shoulders and holding hands and kissing he absolutely does not have time to unpack that feeling especially if it could in any way derail this thing buck is going through.
and eddie knows buck like no one else, he knows how buck's struggled with feeling rejected and like he's never anyone's first choice. but here's tommy, and he's cool and nice and adventurous and loyal and buck gets all giggly at the prospect of being with him, and that's exactly the kind of relationship that buck deserves to have, one that makes him feel seen and chosen, and this isn't like with his past girlfriends where eddie could be snide and tease and try to help him see how wrong of a fit they are for him, that kind of behavior could really hurt buck here, so eddie is determined that he is not going to ruin this for buck, no matter what, because this isn't about eddie and the weird flutter he gets when he thinks of another man with buck and what it must be like to get to hold him and kiss him.