Jackie your son doesn't "dislike" his daddy, he is just exhibiting typical toddler behavior. This means that most toddlers (those without certain special needs) throughout the world and throughout time have done this, are doing it, and will always do it. You did it, and your husband did it. I did it. My kids have done it and are still doing it. In fact my husband (who has no knowledge of child development) got upset just last night because our 2 year old played favorites. In some kids it is more obvious, and in others not so much, but it happened to us all.
This type of behavior is crucial to your son's social & emotional growth. It is how he learns independence, the pragmatics of relationships, control, loyalty, love, security. This is actually a HEALTHY sign that he is growing up in a good environment.
Please please understand that he should never ever be punished for it. Of course you can tell him that it hurt daddy's feelings, that's is our job when we teach them about life, but you need to allow him to do this without fear.
Yes it hurts the other parent. I have studied this in my graduate work, yet when my daughter rejected me for her father when she was 1 I was devastated. But I knew what it was and that it needed to be done and that it would not last. Now, at 6, when we tell her about that she cannot beleive it because she is such a mama's girl.
Find a good parenting book to share with your husband so he understands. I know alot of mom's here will have good book recommendations. My best to you.