How do I stop feeling lonely?

I have a great boyfriend and afew friends but whenever they are all busy and I'm home alone I feel lonely.  Like sometimes my boyfriend will have to go somewhere on a Saturday night and i ask my friends and they are all busy so I sit at home and feel bad about being alone on Saturday night. Whenever I'm busy my boyfriend always finds someone to hang out with but it not the same for me.  How do I feel less lonely? When I'm home what are some things I could do to make myself happier?