Does Yuuri's heart just break when he realises how Viktor based his skating programs on him? When he learns that he was the motivating factor for Viktor's return from his injury? Does he feel bad for turning away and not watching that first program Viktor choreographed with Yuuri in mind? I would think the depth of their years of misunderstanding each other would weigh on him, especially when he realised how long Viktor was trying to reach him through his skating.
It really does weigh on Yuuri which is something that they need to clarify in their Big Talk. Viktor doesn’t want Yuuri to spend the rest of his life feeling guilty or feeling like he owes Viktor to make up for everything that happened as that’s not a healthy basis for a relationship. But the one thing that Yuuri will always regret is how much more time the two of them could have had if he had just realized sooner. That’s why after they kiss at the wedding he tells Viktor ‘I’m sorry I made you wait for so long’. Viktor is very insistent that they were both at fault and Yuuri doesn’t need to try and ‘make up’ for anything now that they have both apologized and forgiven each other, which Yuuri accepts, but that big regret about time stays for a long time, although it lessens a lot throughout all the happy years they spend together until finally Yuuri is able to let it go