I'm kind of with you in RL, I wouldn't want any of the ORS characters as friends (or partners) the issue is that we have porn characters in a porn game acting on porn logic.
The issue is not so much if Jeremy is terrible friend, its if he is one by the games standards.
What does Jeremy do what Ian, Lena, Ivy, Mike, Cindy, and Alison aren't doing? They fuck around, have multiple partners, have casual relationships and aren't overly worried if they aim for someone who may or not be already taken. It's partly the criticism against Jeremy that gets me (moreso if its factual wrong, like he supposedly tries to antagonize Ian or tries to directly manipulate women), but its also the hypocrisy how he is called out for fucking around when other characters do it, but get a pass because they are either 1. a hot girl, 2. Ian aka me and I can't do no wrong or 3. asshole rivals who are expected to be shitty.
Jeremy only thinks about scoring and doesn't want relationships? What about Ivy, Slut Lena, Chad Ian, casual Emma, slut Holly doing the same? He is slightly manipulative as in he may not tell his friends all the information he has immediately and considers presenting them when its convenient for him? He boasts about his sexual life? He is interested in the same girls as the MC and may not kindly step aside but make a move on his own? Those are character flaws, but they are understandable, fairly consistent, not overly exaggerated to make the characters villains/caricatures.
Ultimately, Jeremy is as flawed as most friends are. We want those 100% supportive loyal superhumans as friends, but just as we they all have their issues and flaws, will get in your way and fail to understand each other in every situation, leading to conflict. Someone isn't your friend if you never had a strong argument and crisis with them and stuck to them afterwards despite of it. Just how Perry and Jeremy can be Ian's closest friends, despite them being shown very flawed, negatively and often a detriment in his life instead of support. Since that's usually how your friends and family is. Now, this can lead into being codependent on abusers, so naturally they have to grow up and improve as well to keep up, else its true that leaving them may be the healthier choice. Perry can improve greatly. With Jeremy there isn't much development. Lena does have a love option with him, so maybe he becomes a proper boyfriend. Maybe he and Alison stay together. Maybe he and Ian embrace being bros and don't pursue serious relationships ever.