Are there any plans to automate the process, so that the "Add Person" button will show "Spouse," and let the sex be specified?
While WhollyGenes never announces explicit plans for future features, I would doubt this would be added. Same sex marriage enters the ever active debate about whether software should focus on "family" relationships or "genetic" relationships. Trying to do both I think would make the software extremely more complicated. WhollyGenes has previously stated that the primary purpose of its "genealogy" software is genes/genetics. In the program the concept of a child having only two parents, one of each sex, is for tracking genetics. At least TMG does not require the two parents to be married, which is required/assumed by many other genealogy programs. As you have discovered it does seem TMG defines its concept of "spouse" as the other of two genetic donors, not the other person in a Marriage. TMG has separated recording the event of creating a Marriage relationship which only involves two people of any sex, from recording a genetic relationship of a child and two parents of opposite sex. That separation is why a Marriage event between same sex partners is so simple and possible to record in TMG. While TMG can express these modern "family" relationships and events, I believe most of its terms and functions and assumptions will remain focused on the "genetic" purpose of the software.
Just one user's opinion,