The MC is your typical weak ass beta feminine push over shit (which kinda saves the story so even though I hate this type of character, I'm kinda glad the MC is a cuck), the author intended it so that in the last minute of the girl's seduction the MC would cuck out (which is the running gag of the other on going manga), this is basically NTR (and the MC is the netori, though not intentional) disguised as "comedy" and their "cute" little interactions is supposed to be the start of their "romance", come on the girl is for the streets, bros before hoes ma men, she belongs to the streets, if she really wants the MC, break up with the other guy plain and simple, if the girl can cheat with her current BF, who says she can't do it when she's finally with the MC?.
This actually shows a bad example for the children who could've brought this in Japan and will think that cheating is okay (well in Japan cheating is quite common, both genders tend to do it).
Either the author is a fan of NTR and a virgin cuck in real life or the target demographics for this crap are those lonely adult virgins in Japan (male or female), pathetic really pathetic, I don't get it why Japan is so obsessed with cheating.
