Almanzo Wilder was significantly older than Laura Ingalls when they began courting and when they got married. Almanzo was twenty-eight years old when they married, and Laura was only eighteen.
When they married in 1885 in De Smet, South Dakota, having such large differences in their ages was quite common for the time period. During the 1800s, women tended to marry earlier than today and their husbands were often older.
Today, however, a ten year age gap is quite unusual, especially when the wife is only eighteen. But for the time Almanzo and Laura married, it was considered ordinary and commonplace.