(SPOILERS AHEAD. AVERT YOUR EYES IF YOUVE NOT FINISHED LEOS ROUTE).
I think you should read this VN not in the sense that youre trying to date one of the characters, but view those characters as having a flaw that you struggle with, and conquering it by playing it out through this VN. For example the MC views Leo as an anchor that is trying to hold him down in this town he doesnt love (he admits it to himself in the 1st or 2nd hallucination). Staying with Leo in this town is obviously not what the Otter wants, even though Leo is such a comfort to be around. It isn't healthy for him and he must take the opportunity that only comes once (the train) to move on from the mistake of his past (murdering Sydney) or be stuck here forever (like having your legs taken away).... In the past they wrote fairytales of a young unwise woman falling in love with an obvious tramp, and as punishment she has to spend the rest of her unhappy life cleaning a home of a person that abuses her. Leos route is kind of a retelling of that fairytale and the moral is to move on and dont let a few comforts hold you down and trap you in a place of suffering. And in a sense Leo has to stop obsessing over the MC. That's his flaw he needs to get over. He didnt drag MC to bed all bloody like that cuz he was in love with him. He did that because he was in love with the idea of being with him and it was turning him crazy. I guess it is because of the trauma of loosing Sydney that he views others as objects instead that need to be possessed rather than people and risk having genuine feelings towards them. He doesn't want to feel that pain again I guess.
I didn't read Jenna's route but all of the characters seem to have a 'flaw' with them. Quite common flaws that me or you might have actually. And reading through their routes will help you find them and in most cases you can steer them away from the bad route and instead guide them to conquering their flaws. Thats at least the way I think when I read this VN. It is quite a emotionally difficult read for me unless I take a more clinical approach...