I am the only diver here in our famiy-unit -- my other half is usually in diving circles refered to as the NDSU (non-diving spousal unit). I am not sure I would necessarilly WANT a partner who dives, and here's why....
....I've got an independant personality. My work requires that, since I spend a lot of time travelling the world. When I travel, I go diving....alone, or with whoever I can dig up locally. If my partner was a diver too, that would open a potential source for jealousy "you went diving in <exciting ocean> and all I have is this crappy quarry"-type things.
Also, much as I love my NDSU and treasure the time we spend together, I like doing things on my own from time to time too. Going diving, for example. Then comming back home and with excitement talk about what I did/saw/experienced. Gives me a chance to relive it all over dinner -- and the NDSU is sufficiently interrested in water to not be bored
The NDSU, symmetrically, has independant interrests and activities, and doing things apart (while being interrested in eachothers activities) gives us lots of stuff to tell eachother and talk about.
Also, I get to meet tons of new cool people when I dive -- rather than always go with the NDSU. Nothing, really, seems so hard to socialize with in a dive-situation as a "diving couple" -- just my experience.
When we go on vacation, we go together, we do things together. It's "us-time" by choise from both of us. Fortunately, while SCUBA is not interresting to the NDSU, skin-diving and aquatic life is, so we have fun doing that in moderation -- as well as all those other things you do when on vacation (romantic dinners, museums etc). If it's a really nice dive-place, I may do 1 day worth of diving while the NDSU goes shopping or some such thing that I do not care too much for myself. More often than not, though, we do not go on vacation to typical dive-sites.....
What works for us, I think, is that we match personality-wise. We're both "independant minds" who like doing things apart. We both like sharing when we're together, but do not insist on being together at any and all times.
Based on my experience, I'd say that the "problem" is not finding a single diver (I know tons of those...) to partner up with, but is in finding someone who suits ones personality -- and accepts that YOU are a diver and need to go dive alone.
What I do think is a hard problem, though, is to find reliable buddies on my travels ;( Is there any solution to that problem?
i guess there's always Viagra I saw a program on TV called Condominium Casanova's.