I know that sometimes we face some news we don't like, or we discover some upsetting fact about somebody that we like. I know that when this happens, a thought may cross our minds: "life is horrible" or "life has nothing to offer". But it is not; and yes, it does offer something, and a lot by the way.
I believe our vision of life is very much what we, ourselves, make of such view. The facts are there, for everyone to see (even though, for many people, they might be hidden or mystified, for example). How we choose to see life, well, is an entirely different matter. Specially since the generalization you do upon the facts you know, it's you who decides to do it. You were betrayed by a boyfriend, so "No man is trustworthy"? It's you who's choosing to think like this. A French person was rude to you when you tried to communicate in English, so you thought every French was rude? An inhabitant from Paris was gentle to you, and you generalized the case to all the population of the city? In both situations, you choose to think so. Sometimes, our generalizations can contribute to happier visions about life.
Of course these generalizations that we do might bear a relationship to what some people call "luck" or "misfortune" in life: that is, the list of people and events we encountered in the past. Sometimes, someone face their pasts and identify disappointments with a long list of affective relationships (sometimes, the list isn't even that long, but is full of disappointments nevertheless).
In such a case, it's up to us to choose to hope that the next persons that we meet, or the next events that we live, will be different. We can even influence such difference, by changing, in the meantime, something in ourselves or in our attitudes so that our future relationship to people and events will be different.