People need to understand that Sasha all throughout his life literally lived in the slumps traumatized, making him mentally-ill and affecting his decision making. Desperate for any form of salvation whether it be settling out of pity from Karel’s love.
Karel was literally crazy for monopolizing Sasha. In Karel’s perspective it’s pretty much selfish for him to think that the only method that could heal Sasha was being their for him and doing everything with him or for him. But to Sasha, without having a definite career and life to contribute in their relationship. This makes him feel like he himself, is a burden and making him anxious about their future.
There’s no point in pointing fingers here especially to Sasha. When in reality Both of them failed to acknowledge that they’re suppose to be doing these sacrifices for themselves, their relationship. Not for the sake of each other.