The story would work just as well with any other classmate/teacher/some random hoe.
Melvin wouldn't need to (attempt to) cuck the MC for the MC to go "oh shit, this is wrong, we gotta stop him"
Look at every other non-porn game and you will see plenty of antagonists without the "need" for (threat of) NTR.
It is the plot now, but I don't think it was >strictly neccessary< to be included imo, as someone argued.
Knowing F95 they would still consider that NTR
.
Also I feel like Melvin going after people closer to the MC makes it a much more serious threat and improves the story itself.
It wasn't necessary like you said, but it certainly established that Melvin is a threat to the one MC loves.
That being said, how would the MC even know he's going after random chicks he knows nothing about anyway?
Another thing, Melvin's initial intent was to use Lexxx to take control over Bailey to become prom king and get popularity along with dating the hottest girl in school.
However things like the MC winning prom king instead of he goes with Sam causes him to become jealous, same with MC taking Emily to the dance or the other scenario where MC goes to prom with Alexa which makes Melvin target Emily instead of going through with his initial plan because Melvin has had a major crush on her for a long time.
Overall, there isn't many lewd games like this and I like it that way. Llama has done a great job with building up relationships, the characters, storyline and the scenes themselves to this unique quality game.
So far I think he's done a fantastic job doing the story he wants to tell.