A movie were this women's husband who is a sheriff dies and she is left to look after there son so she moves to a new town were she has a house and then she adopts a girl who is about 12 I think then they start there lives together then the girl get taken to a farm by a couple and they can't get her back so she runs off with the women's boy and then here and the sheriff go and look for them they are found then the sherrif and the women fall in love.
It gose something like this it is a cowboy, love story and it is oldish

Sounds like Love's Unending Legacy (http://www.imdb.com/title/tt0929864/)