D&C 30

As Peter Whitmer, Jr. was called to serve a mission with Oliver Cowdery to the Lamanites, the Lord provided an interesting and profound counsel to Peter concerning their companionship, instructing -

"...be you afflicted in all his afflictions, ever lifting up your heart unto me in prayer and faith, for his and your deliverance..."  (Doctrine and Covenants 30:6)

Not only is this sound counsel in missionary work to be "afflicted in all his afflictions" (empathy) but also in marriage.