Yes, in fact I'd be really hard pressed to think of many SSM success stories that did not include both spouses. Of the successes I have seen:

You and CAC
Nop and Ms Nop
Im and MissIC
GreenEyedLady and Mr. GEL
Perhaps HP and Mr. HP (not entirely sure of how they were when she left)

The majority of these were couples where both participated. Seems logical to me.

Gone the carvings and those who left their mark.
Gone the kings and queens, now only the rats hold sway.