Some people get used to emotional pain enough that they feel more comfortable in that than they do with being treated good because being treated good is unfamiliar territory to them, something not used to and hence something they dont fully understand.
Ive known people with this type of dilemna which makes it difficult for them to feel and experience Gods love since they have been conditioned not to love themselves so they wonder why anyone else would.
The mistake is reverting back to their safe zone however detrimental it may be as opposed to moving forward and letting God heal their heart.
People are afraid of what they dont understand, and when they dont understand Gods love, of course they are afraid of that too, however much they still desire to experience it.
The only thing that can be done as far as I see is to keep exhibiting Gods love for them until they are convinced its real, be prepared for a rocky ride though, since its hard to love someone who doesnt love themselves.
This is really where Gods love takes over where our own falls short.