>>536028335
I believe it means how deeply they connect with you and how much they see you as their primary friend (or love interest). For example, Smart Falcon is top-right because she truly loves you (hence the top position on the y-axis), but she truly loves all of her fans and has no exclusive bond with you the trainer (hence the far-right x-axis position). Basically, the further right they are, the easier it would be for them to leave you behind.