They say "Why would they get so involved in your life, care for you and make you feel so loved and then leave you as if you never existed?"

Haven't you asked yourself? Maybe it wasn't them. Maybe it was you. You didn't think they'd ever leave up to the point that you didn't care if you don't show them any love and care.

To top it all up you didn't give enough attention and importance that's why they felt as if you never really appreciated all of the things they've ever done.