I think I'm even luckier than Mikey! My wife, April, trains with me as my peer. (as opposed to sempai/kohai) I began training about six months before her and would come back home and chatter incessantly about class. Eventually her interest was piqued and she started too. We started testing together from yonkyu and we both recently passed nidan. (Seven years)
Training together in aikido is a very powerful medium for us to continue changing as individuals and, more importantly, to have the confidence in ourselves and each other to ENJOY the changes. (For the most part anyway.)
As far as training together, we pretty much treat each other as we would any other member of the dojo. While we sometimes exchange a wink and a smile we rarely comment on each others technique (not now anyway, we used to quite alot). Commenting on technique can be a potential pitfall during the first couple of years training together to be sure. After a while one comes to see that they're mostly projecting their own flaws onto their partner (wife or otherwise) and then one stops commenting and simply pays attention.
I am immensely grateful that our situation has turned out as such. Her passion for the art is, at least, equal to mine. Were she not training with me I think there would definitely be some issues as to how much time and attention I devote to my training and our dojo. In the end, as in all things, it's a matter of priorities. The number one priority in life for me is her and she me, (I hope), next is aikido training. We're one of the luckiest couples in the aiki world in that we can meet and enjoy both priorities together, at the same time!