Well to me I think jealousy would bring more to the story. They could try to compete for MC attention and banter back and forth at each other.
This part of your comment, proves that you didn't play this game: IT ACTUALLY HAPPENED, and it didn't end well. It ended with a few characters being shunned and one of them being bullied into suicide and MC literally having a mental breakdown, going insane for a while and choosing to kill himself, then discovering that he was in a time-loop(meaning that everything we saw so far, happened for multiple times), having a second mental breakdown and start to work on things.
Jealousy is not a positive feeling, it's not a feeling that brings out the best out of people. When someone is jealous they're not rational, and they're not having a good time, nor feel competitive(in a fair and square way at least), they feel like they should get rid of competition by ANY MEANS NECESSARY. Which is what happens here, MC favours a girl in particular, the other girls literally bully her into suicide.
I read the manga of Rosario + Vampire, it has a harem trope and competition for becoming MC's girlfriend, in that story, the girls (although it's shown in a silly way, for the sake of comedy) actually fight each other, witch-loli actually use magic to attack her rivals, Snow-Girl freezes everyone around, succubus girl usually is ready to fight by elongating her nails and revealing her succubus parts like wings and tail. Depending on how you portray such a scene, it can be both funny(which happens in both the comic and the anime) or very concerning(because it's still a fight).
What you want is not jealousy but an actual "fair and square competition" for MC's love and affection...but unless the dev has it planned, i don't see it happening in a VN where literally characters can die because they're so addicted to MC's presence, that they do horrible things to each other(including murder).
So if you want that "healthy competition"-thing, this game it's not likely to be the one you're looking for.
