I just feel obligated to remind everyone of the tradgedy tag and the fact that in chapter 1 Takafumi read the book and asked Oji-san to erase everything he just read. Takafumi does not like bad endings, but both Takafumi and uncle have erased their knowledge of any and all bad endings this has.
Up until recently I have been holding out on the hopes it was "tragic" because uncle thought elf hated him and didn't trust anyone. All just bad memories do to misunderstandings. But in recent chapters it has been made clear that was not the case by the end. After all, uncle has opened up, seems to have accepted elf as a friend (from the moment he told her his real name I believe).
But that begs the question, why did uncle refer to her as a stalker with some vendeta against him when it all started? Why does it feel like his own image of her is changing as he rewatches the memories (some of which he erased, but spirits of memory remember and show him anyways). I have to assume its because he is, slowly as he reqatches everything, remembering thoughts and feelings he had erased. He didn't think highly of elf when he met Takafumi because he erased all painful good memories of her by then. And as he rewatches and sees her and what actually happened, he remembers the feelings. Perhaps the reason he walks out durring a lot of the good parts and they end up watching alone is because he saw enough to remember and needed to go and use the "secret teqnique to erase all feelings" in the bathroom. He can't stand to rewatch the non-vauge parts because its too painful for him now.
But he, himself, doesn't know yet what actually happened, why he erased it all. And we will get to watch what happened to him as he breaks a second time from the memories he had erased.
That said, he seems to be forcing himself to watch it as well. You might notice he isn't erasing his memories a second time. Instead seems to be trying to accept the past now that he has the room to drop his gaurd a bit. Hasn't done anything drastic since after he secured a place to live and a symbolance of family in the real world. He erased his memory before securing a place to live with Takafumi, but not again after relearning of Sega's demise. He was safe, so he didn't need to force himself to press on and let himself feel the fall. But still has his limits on what he can relive, and its not being sold for less than a brush that hurts, or being attacked by entire villages and called an orc (used to that). Its only the most obvious intimate moments with Elf, Mable, and Alicia that he walks away from