I don't think there is a definition of a loving parent.
Just in my opinion, someone who can leave their children in such a dangerous position with no thought for what may happen (AND the night after one of the children told then they were crying the night before, alone) does not love their child enough to put them first.
Not sure why such a fuss has been made over this to be quite honest. Wish I had never bothered posting in the first place as everything just gets twisted and picked over by the looks of it. Hell I don't even think the parents are guilty of anything bar neglect 
The McCann's said they couldn't understand what Madeleine meant when she said about her and Sean crying, Kate McCann slept in the children's bedroom the night before, so she thought it couldn't have been then she was talking about, and it was said in a fleeting way, Madeleine said why didn't you come when Sean and me were crying, but then went off to play.
I bet they really beat themselves up over that, it can't be easy knowing that leaving them led to the loss of Madeleine, I expect they hear those words in their heads all the time, it must break their hearts.