Ahem, excuse me Ann but I'm marrying Gray. He is not a girl.
But in all seriousness, I think this was a translation error as there's no female to date in Harvest Moon: More Friends of Mineral Town as its the female version of Harvest Moon: Friends of Mineral Town.
Fuck I don't want to wait 2 in game years just to propose to Gray SOB. At least this gives me time to upgrade and trigger rival marriages.