Most Helpful Guy
Whoever told you that is a superficial mega bitch who is a terrible person. Donating your hair is an incredible testimony to your character as a person. While its true most guys like long hair if you wear a hat you should be ok. Make sure your scalp doesn't get burned. Hair grows back eventually. Don't sweat it or worry about guys and love right now. Do more things like that to improve you character while you are single. Relationships make it harder to develop yourself.
Most Helpful Girl
It will grow again if you let it. It will only take a year to look really good.
A girl that lives in my home town cut all hers off for charity and made lots of money for them. She grew most of it back within the year.
A fellow GAGer has just done the same thing. Made well over her target of £2000. Well done @Taraborelli1997.
Tell guys why you have done it, and true-blue guys will be proud of you, too. They will love you for your generosity!