I just don't know...

I'm confused. Far more then usual. I just don't understand what makes a guy want a second date with a girl. If you go out with someone and you have a great time and its expressed by both parties does that constitute grounds for a second date? When did this all become so complicated? Upon suggestion for a friend I decided to sign up for e-harmony. So far its been 'okay'. I try not to take it too seriously or get too involved with people I meet but its so difficult not to. I found out that my best friend is pregnant and even though I'm insanely happy for her and wish her all the best...I want that too!! I just keep wondering when it will be my turn. I have a great job, amazing parents and friends, etc. Ugh!! It just starts to wear on you after a while. What to do.