@royalbl
that he has no idea how to care for a child is not surprising considering that his kind has no offspring
BUT he clearly knows what love is and he is not an idiot
what I want to say is, after finding that letter he should have given it more thought if he really want to take care of a child which he abandoned exactly because he couldn't bear seeing it alive while she is dead (what is sad but understandable - only why didn't he gave her to a family in his world?) if the answer is yes, then he could have tried a little harder, at least explaining things first since he knows that she couldn't really know and understand anything, but maybe later
as for her, if in later chapters she really just "forget" her family without a reason given, that would be bad writing because from what we've seen so far, she grew up in a loving, caring family who didn't make a difference between her and the biological son who himself also seems to see her as a sister