I wouldn't say that just because he never loves again means he never recovers, many people either only love once, or never love at all, and it is not always because of a previous tragedy, but because they don't find the right person.
The mouse was in his twenties (relative to human years). He had plenty of time and plenty of beasts.
And I don't think he broods for the rest of his life, I mean, it still makes him sad and probably angry to think about it, but I think he accepts it and moves along.
He would certainly brood over it whenever he felt love again.