Okay, I re-read it and while I still didn't like that Ayumi took him to a gay bar without thought for Kotaro's feelings and possible discomfort, I think because he's so eccentric and has always been a little self-centered, he pretty much didn't care about what anyone at the bar said or thought. He may also just be a little clueless due to that self-centeredness. I also read the raws, and to me, I guess Ayumi redeems himself in the second volume.
I was really reluctant about reading this because I suspected it was One Of Those.... Thank you for confirming it (〜￣△￣)〜
While the first volume here on mangago definitely gives that impression I mentioned, it does get better in volume 2, which isn't on here yet. It shows Ayumi's feelings for Kotarou a lot more. I suggest not writing it off completely just yet - maybe wait until Vol2 is available.
The art is great, the story a little cliche. Boy, am I going to get some backlash for saying this, but honestly, I'm not much for plots where super-experienced semes act like they own their inexperienced ukes. And not really liking how Ayumi took innocent Kotaro to a gay bar where they all start talking about Ayumi's past trysts. A little disrespectful, but hey, he's the one in control and asserting his alpha-male dominance over his poor clueless "property," who will end up too smitten with him to ever stand up for himself.