I have this situation. I truly used to think it was DS was like an animal who could sense good and bad people and he'd caught me out. Freakshow!
Anyway, ever since DS was 5 months old (he's now 3 and a half), he made his preference clear. He'll only have his dad strap into his car seat, brush his teeth, read his stories, hold his hand, comfort him if he falls etc. And he'll throw a total wobbly if I offer to instead.
I was utterly crushed by it. But it's not changed and I've got used to it.
My DD loves us both in the way that one would expect That has gone some way to reassure me that I'm not a bad person and that perhaps you know what, it's ok to take shine to another person like DS has.
I know your DS loves you. It's because he's small and doesn't really know the subtle differences between liking, loving and adoration. My DS says he sometimes loves me and sometimes loves his daddy as if he can't love us both at the same time. He probably thinks he must show loyalty to his dad all the time.
It's important that you're consistent, calm and loving despite what preferences your DS shows. He needs you just as much as he needs his dad. He just doesn't think he does. He may have got it into his head that because you are at home most of the time, it means his dad can't be. You know how children can think things.....
Plus otherwise it could work out that he creates a divide and rule situation when he sees how hurt you are. My DS did this too until I figured out that it was important not to let him see how hurt I was by his preference.
It's true that we all expect kids to want their mums when they're hurt or upset but children all skew our expectations!
Take care and bear up. I know exactly what it feels like and it does get better not least because you develop a thicker skin.