I refuse to accept that things here don't matter. [Even if they don't remember - it's how he's able to accept being in love with Robin and knowing ultimately it will end] These moments matter. Even you know that.
... Infants and young children are too young to remember most things, maybe. But that doesn't mean the moments they have with their parents don't matter. [It's the same thing. At least, that's what he tells himself.]