So, I don't know if this will become a harem but regardless, up to this point, this mc is the kind of "dense" that I could put up with. He already has a woman, so it doesn't even click she's trying to seduce him/go on a date.
That, or he's completely aware and he thinks it's "normal" to only be in a monogamous relationship, completely side-swiping her advances. Either way, it's a nice change of pace (so far).
Edit: I'm aware he fucked another girl, but that was right as they got to town and he had basically just became "normal" and it was a new thing for him.