The very welcome sense of excitement when one is turned on by one's partner. It often occurs suddenly and unpredictably after long periods of the couple's intimate complacency. It can sometimes happen when one of the partners mistakes his or her spouse for another person.
Felicia: "What's that look for?"
Horatio: "Your shoulders look really nice today."
Felicia (purring now): mm mm spousal arousal, huh?
Horatio (panting now); Uh huh.