Why don't I ever want to go to parties or hangout with people?

Whenever I get invited to a party I usually don't want to.... Why? Example: this weekend I got invited to go boating with one of my best guy friends, a girl I know good enough and two girls I hardley no. And thinking about going to that.... It just makes me not wanna go. Why don't I want to go to parties like normal people? I'm 14 and I have probly been invited to 10 parties and have only gone to 2. Why do I have this "fear" of gong to parties?