Amazing Sex Life!

When I was with my ex boyfriend we rarely had sex. He was good and everything but I was never in the mood. Now that I'm with my new boyfriend I'm always wanting to have sex. He's definitely good in bed, but so was my ex so why am I so much more in the mood with my boyfriend but not when I was with my ex. Any ideas? (By the way I'm just curious why there's a difference I'm definitely NOT complaining!!)