No, you're not the only one who disagrees strongly with this as a parenting choice. But a parenting choice it is. Dad is apparently allowing the relationship as well. Either that, or he is completely oblivious to behavior of which both his wife and his ex-wife are well aware.
I had my first so-called boyfriend at 16, and first kiss at 17. I had a few crushes before then, but never had the guts to tell the boys that I liked them. (If any of the objects of my affection returned my feelings, they didn't declare themselves, either.
) I do, however, remember my peers playing at going steady as early as age nine or ten -- sometimes egged on by their parents who thought it was cute. For a stretch in fifth grade, playground "weddings" were an almost weekly occurrence. I found that sort of thing as ridiculous and inappropriate back then as I do now.
At what age will Dad and I allow our daughter to date? We shall wait and see. But I do know that if at age eleven she starts singling out a certain person as a boyfriend or "special" someone, she and Dad and I will be having a very frank talk.