I guess I am quite lucky in that my Wife is very understanding and encouraging of me doing Aikido. Currently I go twice a week, however, I have discovered there is a sword class at my dojo midweek too. I think because we have been together for over 10 years, and married for 4 (this August 10th BTW!!)and I only recently started Aikido we are both more understanding of each others needs and wants. She is involved in a spiritualist circle and making friends and having fun that way, I am doing Aikido and making friends and having fun that way!! My wife recently met and spent some time with the people from my dojo, including my Sensei and his wife (also my Sensei!) and thoroughly enjoyed herslf, so I know, even though she is unlikely to take up Aikido as I have, she gets on well with my teachers and dojo mates and will be more than happy to join in with the social side of things which goes along with it!!
Balance as Mongo said is definitely the key!!! I don't think that 3,4,5, or 6 years ago I could have started the art AND maintain our relationship. We have reached the point in our lives where we don't need to live out of each others pocket to know we love each other and that makes a very very big difference!!