Why did kate barlow become an outlaw?

She becomes an outlaw when her beloved 'Sam the onion man' got shot, because Kate and himself kissed. Someone saw this and there next day they burnt down the school house but when Kate went to the sheriff, the sheriff asked for a kiss but she ran away, she saw Sam in the boat on the lake that's when he got shot, so Kate went around Texas kissing men then killing them she robbed every bank in Texas and that's how she became an outlaw.