I don't think there's any rule written down about who can or cannot wear ears or pins. If I understand it correctly, you don't have to pass through security into a special Ears and Birthday Badge room, having presented your credentials, to purchase them. And from that, I'm going to extrapolate just a bit further and guess that even Single People can purchase the ears if they want to! (Horrors!!)
If you and your husband want to wear ears, wear 'em. If you plan to storm up to CMs demanding extra 'perks' you might be a bit off base, but if you're wearing them for the two of you, why not?
This next part may be upsetting to those of a sensitive nature, but I have often seen little girls wearing the Bride Ears (*Gasp!*). Just because they're wearing them doesn't mean they're on their honeymoon, just as wearing an eye patch and a stripey head covering doesn't mean the boys are out pilaging on the high seas in their spare time. I don't think Disney are going to have fits if you wear the ears, and (in my opinion) neither should anyone else.