i think with ilya a big reason he’s, at least on some level, sacred to commit to shane when he first realizes he’s for sure in love isn’t even the fact that he might end up like his mother but that he might end up like his father.
he’s clearly never been in a serious relationship before, the only serious relationships he’s seen in his formative years have been his mother and father (most likely abusive in some fashion at some point) and his father and Polina (her taking advantage of his father at least in some way) so it’s all been pretty unhealthy and not exactly picturesque.
but i think ilya is scared to get into something new and serious and then (irrationally) believe that he will become his father in that new situation. he’s terrified of hurting someone like his mother was hurt, of making someone feel how she felt and god forbid making shane feel like that.
he probably twists it in his head that there will be a day he snaps at shane just like there must have been a day his father snapped. the idea that his father must have, at some point, loved his mother (i’m sure ilya saw gifts exchange hands and small laughs passed when he was very young) and that while no justification will make the abuse right, the fact that there might be ‘justification’ at all is enough to scare him.
it’s a naive thought that doesn’t really come into the minds of people like shane, but he wants to love his dad. he wanted to have him be proud of his games and have him be well taken care of and raked himself over the coals that he couldn’t be there to take care of him himself. and that love, even if it will always be dimmer in comparison to the love for his mother, looks for reasonings. looks for excuses and loopholes that he rationally knows aren’t real, but even beyond that, that he can maybe just push everything that happened to the side for a few hours at a time while he watches his father deteriorate into something much smaller than the looming figure of his childhood.
with abuse like that you want to see a scary monster, something abstract that you have no relation or obligation to, taller and wider than life itself with features you don’t recognize and don’t see again, aside from nightmares and flashes of lightning that light up the figure in a dark room. but you can’t. ilya knows his father was smaller than him - and when he outgrew him he was probably struck with the fear of what he could be capable of - and he probably gets red in the face with frustration in the same way his father did - like in the hotel scene from when he shoved himself away from the vanity to try and find an escape from thinking of shane before he could even see his face resemble his father in the same way it did when he was mad with his mother. (not because he thought of shane in the way his father did his mother, but because of the fact that he might even think of what his father would have done)
he probably thinks it’s in his blood, as much as his mothers genetics are in there he’s not dumb enough to not consider that his fathers genetics simply aren’t at play at all. he loves shane in ways he never has before, and the only love he’s ever been exposed to has been soaked in something rotten and sour until most people would have to hold their nose to get near it but it’s still the only smell he’s ever known to call love.
and he knows what love looks like in his genetics, and besides small snaps of true affection, he knows he doenst want to see most of that again, and he probably thinks that loving shane is putting shane at risk. his dad raised him to be rough and uncaring on and off the ice. but he knows vulnerability on sex because that’s 90% of where he got to have it in russia since it’s the one place his father couldn’t touch.
when his affection for shane so obviously bleeds beyond sex to the point he can’t ignore it, he needs to handle not just his relationship with shane like it’s a something fragile and sharp - despite the fact it’s something he wants to hold it closer to his chest than he has ever held anything - but he also needs to hold himself like his heart is a ticking bomb counting down in numbers he can’t read and only believes exist out of the lingering shreds of love he has for his father.
he doenst love his mother any less due to whatever affection he has left for his father, but the feelings coexist in a messy, conflicting, scattered thing that can’t be untangled much like the marriage he watched crumble into the death of a good woman defines the wrinkles of his brain.
but he loved shane enough to work with it, not ignore it or shove it down but face it head on to defy both his country and everything he knew about love just so that he could do his best to love shane, simultaneously learning two new languages to do it all.
what a scary, scary thing.