Berachos 5b

The Gemara says that someone who had children who died, is receiving "yissurin shel ahava," troubles from love. Rashi explains that this is because his mourning for them atones for his sins. The problem with this is that the gemara on 5a first brings up the issue of "yissurin shel ahava," and Rashi over there defines them as: "The Holy One, Blessed Be He, causes him pain in this world although he has no appropriate sin to account for it, so that he should get more reward in the world to come than he would otherwise merit." If that's the case, how come Rashi over here says that the mourning atones for his sins? The whole point of "yissurin shel ahava" is that there are no sins for them to be atoning for!

I found that the Maharsha asks this, but he doesn't answer.