SOLVED: Older man, younger woman, saddle

I am looking for a book I read ages and ages ago.  Hero is older stepbrother, I believe.  Heroine was young teen when he realized he was attracted to her (maybe 14).  If I remember correctly, he is placing a birthday gift of a saddle on her bed while she is sleeping when he realizes.  He stays away from her until she is old enough.  I want to say it's set in the southwestern U.S., but I'm not sure on that.   Hope this sounds familiar to someone   Thanks  in advance for letting me pick your memories.