It's just as BlandChili said, and when he had the option of telling Ian about it the next day at Wade's birthday party, he couldn't due to him doubting, work, or both related (Which it seems like the bro code is alright when it's easy, and when it matters is.. well, let's wait to the next opportunity and that will fix itself).
Him doubting open multiple branching points, one of them being, Ian telling Jeremy that he is falling for Lena, Jeremy and Lena situation at Ivy's place, and then Jeremy finding Ian and Cindy making what Ian told him a lie (or at least, he is not 100% committed to Lena), making Ian-Cindy-Wade situation worse than Ian-Lena-Jeremy.
I can imagine, depending on how Ian / Jeremy reacts to that aspect to one or both of them being hypocrites in certain paths.
I'm curious how Eva will manage that.
We already saw Lena cheating while being a victim of that same reason (Axel cheated on her), and Ian doing that as well, despite being implied that Gillian cheated on him. So both MC went against their initial moral compass in certain paths.