A person at the office that one shares all the trials and tribulations of the job and outside personal life with--also rumors, gossip, etc.-- on an emotional level. The first one someone runs to when something big happens in thier personal life or at the firm. An emotional relationship, but not a physical, sexual one. Relationship is confined to the workplace--if it goes beyond that, it is more than an office spouse.
It must have been something big, because after the meeting she went straight to Malcom, her office spouse.