"Partner" tends to better describe mature stable adult relationships better than any of the suggestions. Without a huge set of religious conditions, "husband" and "wife" carry no more baggage than "partner" used in a business context.

Others have pointed to the juvenilization potentially implied by "boyfriend" and "girlfriend." Furthermore, "-friend" fails to connote the appropriate level of commitment - even absent the impact of Facebook.

"Partner" cuts through messy reality. Polyamorous relationships. Separated spouses. Concubines (and their male counterparts).