So it was a slow abandonment, stringing him along before she disappeared... or passed away; it's not entirely clear, but that's not a detail he needs to force him to clarify. Either way, for his own mother to drift away from him... of course that would hurt.

Which is why he frowns when Teo tries to downplay it.

"There's nothing stupid about it... she left a wound on your heart. Injuries like that can be the hardest to heal... if anything, I should apologize for pushing you to remember such a thing on a day like this."

The flower festival, he means. He got the chance to do something (theoretically) fun and relaxing, only for him to ruin the mood with subjects like this...