really interested in how ilya frames his mom (understandably) as being this angelic, supremely good figure. and it makes sense obviously, because she definitely was more loving than ilya's father and alexei probably didn't really get along with ilya, so of course ilya would cling to his mother. and of course she died in such a traumatic way for ilya at such a young age he basically paints her memory as being this perfect, ever-nurturing figure who was so sad but loving and funny. but because he does remember her as being very sad i find that interesting.
i kind of picture irina as a very well meaning mother, and who was a good mother, tbf, but not perfect. when you are depressed, it makes you have a lot of blind spots and act in ways that aren't healthy. i feel like irina would feel so isolated. she, who maried an older man very young and quickly had children. i think alexei was naturally (though she loved him) more "grigori's kid" while ilya was hers.
i think ilya would naturally be very protective of his mom from an early age, clinging to the parent who showed him love and affection. he'd try to get in between fights, trying to stop them, and would pick up on the reasons his mama and papa were fighting.
and naturally, because it seems as if she was very isolated, i think she would start to emotionally confide in her youngest son. she'd cry, he'd ask what was wrong and she, who is also a young woman with no one to turn to, would turn to her son. she would tell him how depressed she feels (probably softening the language for ilya because she is cognisant of the fact that he is a kid), and about the problems in her life. and ilya would be there to emotionally support her. i think ilya would also feel really good about the fact that he is the one his mama is turning to, and would try to comfort her as much as he could.
i'd imagine there would be many days where she would not be able to get out of bed and ilya would come find her and try to cheer her up. or after an argument with ilya's father, irina would tell ilya that he should never treat a woman like that and tell him that he already has a much bigger heart than his father.
maybe ilya would learn behaviors to cheer his mother up, he'd naturally "mature" much faster and take on responsibilities naturally.
none of these things would make her a bad person, but just very flawed. and of course ilya would think, "my relationship with my mom was great" and not see any emotional enmeshment there, even if someone pointed it out. because for ilya, he was doing his duty as a son by being there for his mother while she was alive. in fact, he wishes he could have done more because part of ilya feels like he failed her, ultimately. the only person who ever loved him until shane.
so of course he thinks of irina and thinks "my mother was the perfect mother" and probably never unpacks the darker moments of seeing her at her lowest because his feelings in those moments were never about ilya, it was making sure his mother was okay.