You'll get it in the phone-supermarket (from Karen) when you have an orange heart (or higher) from a guy.
The Blue Feather costs 1,000G.
Just buy it from the place you did.
Rock's Heart colour need to be red before you give him the blue feather.
Sadly you will have to buy another one from the supermarket.
To get the Blue Feather you must have gotten an Orange Heart with one of the bachelors. After that you can buy the Blue Feather by calling Karen's General Store during the hours it is open. It costs 1,000G.
it is the same way as harvest moon ds you buy the blue feather, get 60 harvest sprites and propose you have the wedding in a week. by elimac3
Once you have the blue feather you can purpose to a Girl.
well to get the blue feather one girl of your choice has to like you at the MAXIMUM level then you can buy the blue feather from the supermarket (for harvest moon ds)
you have to get your persons heart up to it least orange then you can buy the blue feather at the supermarket once the person's affection is at least 50,000, the blue feather will become available at the supermarket(you can find out the affection the person has toward you by getting the love ring at the sprite casino.) the affection needs to be 60,000 so you can propose
You can Purchase a Blue Feather From Karen's Shop after you have reached an Orange heart Level with your Lover
A year after you get married with the blue feather.
well to get the blue feather one girl of your choice has to like you at the MAXIMUM level then you can buy the blue feather from the supermarket (for harvest moon ds)