"To take something in stride" means to manage something without much effort.

When something unpleasant happens, a person who takes it in stride does not become hysterical and go to pieces. He deals with the problem in a mature manner. Let's say that you are walking down the street and it starts to rain. Some people might go to pieces. They might scream that their beautiful clothes are going to get wet or that the rain will soak their hair, etc. A person who takes it in stride would try to take some helpful action. Maybe wait inside a store until the rain stops. Maybe buy a newspaper to cover his head. And maybe he would continue to walk if the rain is not too heavy. He would realize that the sudden rain did not mean the end of the world. He would deal with it in the best way that he could think of. That person who took his childhood in stride did NOT blame his parents for everything. He realized that his parents did the best that they could. If his friends lived in a big house, but he lived in a small apartment with his parents, he did not cry, "Oh, I am so unlucky!" He would just do the best that he could in that small apartment.

A stride is a termed used in track and long distance . It does not mean easy. It means running at a good pace. In Fantines case. fantine was a intelligent women which is why her pride killed her . She was fooled by a man who played her very well and good . Their love was at a stride which means at a great and decisive step. yet she yet she never saw it coming . That's what a stride means

It actually means that he took her virtue and her innocence as if it was nothing

That lyric (from Les Mis) is a bad (untypical) use of the phrase. Generally it means 'to manage something without much effort' as Randy said, and is a good thing. In "I Dreamed a Dream" it's a bad thing, the French translation makes it plainer, "Et puis un jour il est parti / En m'ayant volé mon enfance" - "and one day he was gone, having stolen my childhood". Clearly a bad thing. A better example: "I took all obstacles to learning English in my stride".