I just finished Leo's route and I'm really distraught from it. (The rest is spoilers)
I loved Leo but to me seemed rude to everyone accept Chase once you got further into this emotional rollercoaster. It proves he is a bit rude by going on Flynne's route. He is mean to Flynn because Flynn is curious to what happened to Sydney and does not know how to ask for the truth.
But I also get why Leo's the way he is. He was stuck in wondering if him and Chase were going to get back together. I have been in a place like that. I understand what he is going through and I feel a lot of sympathy for him.