Are you absolutely certain that it’s not Janette Oke’s Love Comes Softly? That’s the plot, right down to the lean-to. Was there a scene where they were planting corn in the garden and started to have a good time, and realized they might actually be falling in love and freaked out?
And to the rest of you: Oh, shut up. I was a voracious reader as a kid and it was what my mother kept in the house.