First of all, I NEVER support cheating as I believe both person involved in relationship should communicate and end things if are done with eachother rather than cheating unless it is their kink/fetish(just mentioning so you don't think I support cheating or base a "false narrative" of me).
Now coming to the difference between Ian and Jeremy,
Are you sure HE(Ian) is driving wedge between them!
In case of Ian WadexCindy are already on the verge of breakup while in Jeremy's case he knew that Ian is in love with Lena and is looking forward to go to next stage of there relationship. You can see Wade is not changing his ways to keep Cindy and is doing even worse for himself and the path he is choosing is most risky and TIME COMSUMING.
Another thing IMO none of them(Ian or Jeremy) is less than the other in terms of cheating whether they are weak-willed potato potayto or strong-willed opportunistic. All three of them are Bros together and are from high school IIRC. So IMO saying that one is better/worse than the other is
absurd idea to begin with. There is no comparison.
CHEATING IS CHEATING! BETRAYEL IS BETRAYEL! Period!