I feel like Shane seemingly resenting Ilya for being in a shitty team during their fight is because of these things:
Their rivalry and ambition re:hockey is a huge part of their dynamic. Now that's shifting.
Shane is the one who suggests this plan, yes, but Ilya is the one who decides he's ok with it. It is absolutely both their choices equally. Like. If Ilya really has issues with giving up hockey for Shane or whatever (not quite what happens but ok I get it), he could have easily said no to Shane's suggestions.
Shane is ambitious as a person. Ilya's ambition fluctuates a lot with his other motivations (like proving smth to his mother or father, for example). Which is confusing if you're not inside his head to understand why.
I think, throughout the Long Game, Shane notices that Ilya is going through something. He's also going through several things. And they're both stressed about the ways queerphobia affects their relationship directly. And he tries and tries to get Ilya to share what's bothering him or to seek help and offers as much comfort and support as he can. But Ilya always makes it a point to turn him down (rudely even coz he gets spooked).
Also, throughout the second book, every character is always judging Shane for being Too Much and Not Enough. They're all like omg u care abt this thing too much. Omg u don't even care about this other thing enough. And hockey is also included in this. Ilya monologues internally about how he's not as obsessed with hockey like Shane is. (And this is why he know the dark side of the sport in ways the wasian man isn't....ok...). So Shane is entirely alone in most of the things he stresses about. The hockey. The queerphobia. Etc.
So now you have Shane who is absolutely noticing that Ilya's new team is not good and it's bad for his career ambitions and he's trying to ask Ilya how he feels about all of it. And everytime, Ilya brushes it off and/or claims he's extremely happy actually. (And he IS happy to be near Shane, after all. He likes his teammates and his coach and he's got Shane and his parents and he's a LOT less lonely than he was in Boston. But he's also depressed ofc).
So now Shane has to suppress all this worry because seemingly Ilya is totally chill about all of this. And so all his doubts about Ilya's hockey ambitions has nowhere to go. I think he actually feels kind of abandoned in it! And when they fight, he throws his confusion as a kind of resentment at him kinda.
But he's never not known that Ilya is making changes to his life for Shane. Shane himself is trying too.
I'm saying. To someone like Shane, choosing to be with Ilya in secret is already a huge fucking risk. Shane is taking that risk. He came out to his parents and invited him to the cottage etc etc.
They've always interacted with hockey as the center. And for Ilya to abruptly decide that he doesn't care about hockey and also that he doesn't want to be in the closet and also that's he's fucking depressed and suicidal, specifically due to his team and career trajectory even, all without telling Shane literally even one piece of information is absolutely insane lol.
Wudnt u feel abruptly lonely if u think both of u care abt hockey n suddenly he doesn't care abt anything at all. Not the hockey or the closet or the romance or the city or anything.
Ilya himself has a lot to lose by coming out too. He's the one who will never be able to go back home if he's out (so they say). He's the one who will have to take a risk with a Canadian or American visa or whatever if he cuts off all ties to Russia. At this point, he's just emotionally done with Russia. Iirc he wasn't happy in Boston either. He has not yet literally severed all escape routes. He should also care a lot about coming out. There is nothing wrong with Shane being super confused about his sudden shift in attitude. It doesn't show disrespect but actually just a more pragmatic view of their future, that's all.
This is a story of a man who feels like he can never go home and his lonely lover who welcomes him into his and also wants to build one with him in the future. That's why they're both really happy with their manic plan lol.