It's extremely difficult, if not impossible to imagine a world where nothing ever goes wrong. So it's very difficult to answer the question of whether Love, say between a mother and her daughter, would develop if she were to experience a childhood where there were no grazed knees, where towers of bricks couldn't be knocked over (unless she wanted them to be), where ice creams didn't melt and plop onto the car park and where other children never bullied or were never nasty to her.
We don't live in that sort of a world, but my guess is that all Love needs to develop is relationship.
Perhaps it would help if instead of trying to consider a childhood in a world of which we have no experience, we compared two childhoods that we really can imagine.
The first is the sort of childhood where all the usual mundane things that go wrong in every child's childhood, do happen. It's a childhood of grazed knees, stubbed toes, bashed funny bones, popping baloons, frustrations, disappointments and the occasional cold thrown in. It's also a childhood of hapinesses, of sunny days spent buiding sand castles, of the fascination of lego, of playful loving parents and a warm snuggly bed at night.
The second is the sort of childhood with all the same bad things. Ony in this childhood experience we'll throw in brittle bones, chemotherapy for childhood leukaemia, a father dying prematurely and a house and possessions, with all its familliarity and security, swept away by a tsunami. - I've deliberately not included suffering inflicted by other humans here, because it can cloud the issue.
The mothers in both our scenarios show tender Love to their children throughout. Does the child in the second scenario learn to Love her mother proportionally more because of proportianally more suffering? I don't think anyone would agree that more suffering brings greater Love.
So while there may be something to the idea that, for the normal interplay between mother and child to take place - an interplay in which Love grows, there must be upsets, failures and disappointments as well as happiness, successes, and satisfactions, I don't think that such a notion gets us around the problem of evil. The sorts of massive tragedy that we've just witnessed with the Japanese tsunami, the horrendous suffering caused by disease and genetic disorders, all outside of human control, can't be said to be necessary for the ability to learn to Love. Oh yes we need Love to help in such situations, such as we can - comforting the victims, offering practical help and assistance, giving of our time and energy to research treatments and cures etc. but these events and circumstances that cause us to suffer to the point of breaking, are not explained away by the notion that, for God to place humankind in a world where humans could develop the ability to Love, God had to allow these dreadful things to happen.