Considering the MC's girlfriend inevitably meets a new "male friend" like, 2 events in her storyline, and the only choice the player gets in this regard is whether she's going to talk at length with MC about her sexual activities with said friend, or engage in them behind MC's back, probably prudent to give this one
netorare
/
netorase
tag(s)? Not like it's any real surprise in this genre, but you know.
edit: unrelated, but
I have limited time and energy to work on my projects. When I sit down to write I want to toss this little idiot into the fire and torture him. And I hope to make people happy by letting them live out their submissive desires vicariously through his torment.
Something to keep on mind: while, as a dev, you can get your rocks off effectively being a sadist towards a pathetic sad sack, the player doesn't have this option. They are forced to inhabit the shoes of that sad sack, and to be placed on receiving end of such hostility and contempt (something which bleeds through the writing) can be too much for many and limit your audience. There's difference between submissive desires and being plain hated and abused with no respite. The latter just gets tiresome (and dare i say, boring, because it's just mashing the same few notes over and over) quickly, like bad goth poetry.