Why dont i have a boyfriend?

Okay so im almost 14 and ive never had a real boyfriend, as in more than a day or something. Ive ame very close but it never works out. Ive been asked out probably 6 times but i havent liked any of them. I have a lot of friends (girls and guy) and there arent really any people who do like me. People always tell me how pretty i am, so why havent i ever had a boyfriend? Oh and btw when ever i like a guy i let them know how i feel so thats not the problem.