Riggggght? Specially when he said "if I'm single I'll go for you" what a turn off, good thing hibiya draw the line, he was already off on how he wants the uke's attention in the first story "push and pull strategy" show's how self-centered he is. Now this?! Like boy who do you think you are? I don't know just the way he treats his co worker really put me off, he didn't really redeemed his character to me such a red flag.
The break-down! Omg thanks for this I thought I was crazy!!! ‘Cause some of the comments are like he’s just like that kinda flirty and now he’s nice and kind like Yoshino, yey! Wtf? A person in a serious committed relationship can be kind without being flirty!!! And overall, just what’s with the weird tension? I get this ick when I read his scenes with the co-worker, it’s weeeiiird. He’s cheating fr. Idc about the comments that says other wise. They need to break up. Even all those comments defending that cheater of a seme knows Yoshino deserves someone waaay better. :))

It's been ages since I commented anything. I'm locking in, let's over-analyze.
Some comments are way too lenient with the seme just because he didn’t cross any sexual lines and he’s not an obvious red flag (arguable ik). Also just because it was a one-sided crush on the seme’s part doesn’t mean that wasn’t emotional cheating. You can deny it all you want, you can say I’m overthinking, but here are the facts: most of the story is about the buildup of the tension between the seme and the coworker, the seme begins prioritizing the coworker and crosses personal boundaries, and the uke tolerates it because he idealizes the seme as a ‘kind’ (?) person who wants to help others. The way it was portrayed was as though the seme was slowly falling for his coworker rather than them becoming mere friends. Let’s just be real. He was at the very least attracted (the mangaka said so btw, that they created a character that would catch the seme's attention despite the fact he has a bf) and went with the flow because his mentality is “I’m taken what’s the worst that could happen.” Immediately embarking on a slippery slope.
Genuine question to those who defend the seme and tell people like me to touch grass because I can’t comprehend ‘mature relationships:’ how would you have reacted if you were in the uke’s place? Not even just the moment where the seme said he would have dated the coworker if he was single, but their entire dynamic. Like the seme being overly attentive, gentle and considerate of him at work and butting into his personal life. Notice the difference in speech too. When describing the situation to the uke, he speaks about everything much more mechanically (“he’s in bad shape, I’m taking care of him”), while acting more suggestively/ intimately with the coworker (“I will be with you until you stop crying” etc). Imagine your partner -let’s say you are in an exclusively monogamous relationship- doing this to a COWORKER, and staying over at said coworker’s house for DAYS or more to 'comfort' them. What the actual fuck. He did wayyyyy too much. Him staying over at the coworker’s place and taking care of him in his free time, pretty much indefinitely (until he ‘stops crying’), while meeting his bf like once a week was worse than anything he said, imo.
Also. Little experience with relationships? It's just his character? MISS ME WITH THE BULLSHIT. So you’re telling me the seme was sharp-witted enough to pick up on the fact that something was wrong with his coworker and had this super deep convo with him about love and commitment, but somehow has this conveniently selective self-awareness when it comes to his own behaviour? This contradiction, this selective self-awareness, while amusing to the mangaka as per the afterword, proved to be a poor vehicle in their relationship’s development. That is, as a reader I now have even less faith in their relationship.
The seme is a looming disaster. He’s a way milder version of the cheating semes from Yokosu Inu Mekuru Yoru and E-Series 1. Imagine how far the 'caretaking' could have gone if the coworker didn’t draw the line between them (though he did begin to waver a bit at the end of ch3). If the seme didn’t get that text from the uke’s friend. He snapped out of it only when others spelled it out to him. Zero growth. He is always on a slippery slope. Just because it wasn’t malicious and he didn’t suck the coworker’s dick doesn’t mean he is suddenly morally justified and people are overreacting. But omg he apologized and promised never again and they hashed it out with sex. Yeah, no.
The reality is their relationship doesn't crumble solely due to the uke accepting and forgiving everything. The uke carries all the emotional burdens to preserve the relationship, just so the seme can ‘be himself.’ Mama, run. This was just the hill, what’s the mountain gonna be like?