You'd think if they even hugged once in that 6 months she'd be able to tell.
i thought everyone's relationships started with six months of really awkward side hugs
I thought it was two or three years of awkward glances, then side hugs, and then hugs. And of course once they're married the real lewd stuff happens. Y'all know what I'm talking about. (If they're especially kinky they might even interlace their fingers during... that.)
Now as for the comic itself, I can accept the sudden big boobs and only realizing she's a girl after six months of dating for the sake of comedy. It's funnier if it takes an unreasonable amount of time, and when there should have been such an incredibly obvious clue.
I enjoyed this quite a bit, I hope it gets more chapters. Also these two are just like Yamada and Kase if Yamada was less shy/awkward and Kase was less useless.