I don't belive it is so important that couples share a passion (e.g. climbing), but that both parties have a passion for _something_ so that they can understand the other's passion and hopefully support it, either as an active participant, or by being willing to share their time with that passion (climbing as the 'other woman').
Been all three places - former gf/fiance who had her own passions, but did not recognize my climbing as such - A portion of her relationship philosophy, which I bought into for some time, was that couples should do everything together - well it is good if they _can_, but harmful if they _do_. I lost a good portion of myself during the later stages of that relationship - it's tough to put yourself into a lose-lose situation - guilt for spending time with her rather than taking care of myself, and guilt if I was out climbing rather than being with her.
Second - Separate passions - She climbed, but not at a very high level, and recognized that I needed to go play. She also had her own passions - gourmet cooking, clubbing, etc. A fair balance was worked out for a while - separated for other reasons/issues/no long-term compatibility.
Third - Shared passion for climbing (she started on her own), although she does not have the time, or necesarily the goals, of pursuing it at a high level. However, as time allows us (she is stuck in Retail Hell), we can get out together. Conversely, when she doesn't have the time, or I have big numbers or long routes to chase, I have other partners who I can call on. A fair balance can be reached, but vigilance in making sure the other is doing well in the relationship in general is a must.
Not much - just observations - and still a work in progress, as always.