I agree with the other mothers and say to you gently, "You are not a bad mother." I too am a full-time mommy of a soon to be one-year old boy. We are married to the military, so daddy is gone much of the day and generally has evening responsibilities. So, it's generally just me and our son. What's interesting, is that he is generally more fussy with his daddy then me, which is opposite of your situation. Go figure!
We are going thru some bedtime anxiety and well, seems as though mommy is the only one to calm him. So I can relate when the question as to "why?" comes to play with mommy vs. daddy no matter what the given situation is or behavior exhibited.
A few things I (we) have started: My son and I just joined a Baby Gym class with 6-12 month olds. It's fantastic!! This way, our son is gaining exposure to other people and ya know what, today at his first session, he did great and was able to wonder all over and away from mommy. As long as he heard my voice and could turn and see me every now and then he was just fine. Perhaps joining a play group to expose your child to a different environment beyond only the two of you would be good.
We too have a date night every other week along with me having one weeknight or half-day on a Saturday to do my own thing. I think it's critical to have "you" time let alone time with your partner. I also am a firm believer in making sure the two of us are on the same page when it comes to parenting. Granted, we will stray every now and then only because he's daddy and I'm mommy; however, when one of us finds a parenting strategy that works, we share to ensure we both are consistent. This way, our son does not attempt to manipulate or perhaps fuss. Granted, we are well aware that children will test our parenting and patience, but I am a firm believer in consistent parenting to avoid trival battles in our home.
And just remember, our children are going to respond differently to different people and well, this includes his own parents : )It doesn't mean he likes one more than the other.
Well, best wishes and remember to take care of you!!!!