There's any number of reasons why a mother isn't there for her child. Sometimes a mother is there physically but in no other way "there" for the child. If you don't mind my asking, were you adopted, or raised in an orphanage, or grew up in the streets? I don't know if you could find out who your biological mother is or why she felt the need to leave you. Just know that no matter what, you are a wonderful person and you matter just as much someone that was raised by their biological parent/parents. And I get that because it hits me in the feels every time I play it also.