Lets not debate this. As many Sorrows and Happiness are part of Life. And believer or not , everyone has to go through his/her share of the two.
According to ISKCon, the International Society of Krishna Consciousness : Even a believer of Krishna, will go through the same cycles of Life; that's the Cycles of Happiness and Sorrow. Thus Krishna doesn't make the Life of his believer, the bed of flowers. What the submission to Krishna, as Supreme Lord, does is: It help the believer tide over the Unhappiness , better than others. In simple the faith on God or believing in some religion or faith helps the individual to face the lows in a better way.
I think, this can be applied to any faith or religion across the planet. A recent study also proves os: Faith in God helps a person manage unhappiness in a better way.