It's about two students in the same class who realize everyone but them is in a relationship. They are kind of forced by their classmates to go out with each other, even though they don't particularly like each other.
I remember the cover of one volume being the two main characters in front of a class board. There is also an otaku couple (one acts openly, while the other is a closet otaku).
I read this manga once and really liked it, but can't remember the name.
It's most likely Bocchi na Bokura no Renai Jijou.
The color spread from chapter 1 indeed features the main couple in front of blackboard:
Synopsis from mangaupdates:
When summer break ended, high-schooler Ichijou Hajime finds out that everyone in his class but him has gotten a girlfriend or a boyfriend! Hajime suddenly finds himself a loner but then Ninomiya Chitose transfers into his class...!?
Since they are the only loners in the class, their classmates suggest them to go out with each other. Of course, they vehemently refuse the suggestion, since they just meet each other. However, the boy makes a faux pas when he says he doesn't want to date her just to make do, which the girl responses by saying that he is "unsold good". This marks the bad start of the love story between them.
As for the otaku couple, here they are:
