I have something to offer on this topic. I do not believe that my parents have stopped "loving" me - at least, I don't think they would feel that in their own minds.
I know that they have been brainwashed and that they believe that what they are doing by shunning me is right. I know that they hope and pray that I will come back to the JWs and that everything will be alright somehow.
But in my opinion, limited as it may be, what they profess to feel for me is not love as I would have it. It is a small, imprisoned thing, dying for lack of light. It is twisted and it is very, very sad.
And yes, it's conditional. Comparing the love between a married couple and between a parent and a child is not really accurate - at least I've never felt that way. There should be a bond between mother and child, or father and child, that is stronger and deeper than any other.
Maybe I'm naive or expecting too much. Maybe I'm just still angry at my own parents for never figuring out how they had been suckered by the JW organization.
Enough about that - as far as anything outside parent/child relationships goes in the JW congregation, I do not believe that many JWs feel real love or real loss when someone they know is Df'd.
JWs are trained to love the organization above all else - family love makes its presence know because that's hardwired into most of us as humans - and the Society hasn't been able to undo our "unwanted" genectic traits, at least not yet.
I would say, allowing for exceptions - because they are always there, most JWs never understand what true love and/or friendship is. That is why they are able to stomach the practice of shunning.
Whatever lies you are told about shunning, whatever lies you tell yourself, it is wrong. It's a tool of control and people that practice it are allowing themselves to be used as the hammer.
I used to be very angry when discussing this topic, and although I can still be sometimes, mostly I feel very, very sorry for those people who live a life where shunning is considered normal and healthy.