TL;DR: For those bitching they haven't fucked yet and should fuck already, fuck on off to a hentai website or something.
What makes this manga fun to read is the slow exacerbating anticipation to full-blown sex and the progressing foreplay. The achingly-slow progression as they get more boldly intimate with each other because their sexual desires increasingly stifles their sense of logic and morality. Sensei wants to fuck him, but her loyalty to her marriage and not wanting to be taking advantage of her former student is getting in her way. He still refers to her as Sensei; like someone above him instead of by her name as with someone on equal terms would do. Aki-Kun wants to fuck her, but he's confused with whether he just lusts after or loves her and risking destroying her marriage. He also doesn't want to hurt his closely-attached female assistant who wants to pursue a romantic sexual relationship with him: so he's playing games all over the place and we see how he tries to justify/handle them.
What makes this manga great is watching two people trying to be good illogically but humanly slowly justify full-blown fucking each other at the expense of their morality and people closely-attached to them. If they were just scumbags and fucked instantly, it'd be a boring cheap hentai. Also, once they fuck then the manga is over or (at best) it goes into the next phase where the readers see the repercussions those two need to deal with and consequently follow the manga's conclusion soon after.
Again, either drop this and fuck off to some hentai if you can't enjoy the anticipation or shut up and enjoy the bumpy ride.