So hear me out on this, right?
So in my personal headcanon, Butch and my Lone Wanderer become friends and gradually fall in love like a year or two before James leaves. In terms of Butch's friendship with both Wally and Lone, the closer he is to Lone, the further from Wally he gets. I like to think it's because Wally Mack symbolizes Butch's anger and cruelty, so the more in love with the lw he falls, the more he lets go of his self-doubt and anger and cruelty.
Wally indulges the persona Butch had thrust upon him his whole life — the no-good son of a lush who will never amount to anything.
Robbyn shows him that even despite everything he's put her through, there's more to him than that, and that he is enough as who he really is.