Years ago, I was sitting in bed talking with my girlfriend, and she was explaining to me that in the future after we have broken up, Vanessa didn't say why we would break up, but she just assumed that we wouldn't have a ten year anniversary, and we didn't, so maybe she is magic? But anyway, she verbally made a list of the women in our peer group that I was not allowed to sleep with after she had finished with me.
I think Vulcans might have a similar protocol.
If the unthinkable happens where man and wife are separated during mating season, and the stark reality is that if they don't get busy with someone else, that their plump brains will explode like pulp panoramically out their ears, nose, mouth and eye sockets. If that is the consequence of loyal chastity, only a moron would be loyally chaste, and only a sociopath would force their spouse to be loyally chaste to death just because a plane was misdirected by a blizzard or some other random twist of fate.
(You have to see where I am going with this.)
Each half of the marriage writes down 5 names of persons that their lover is not allowed to ever-ever frakk just because their life is on the line. Pon Farr is not a loophole of a hall pass or a freebee, there are rules, and those persons on that list are all still a series of huge giant read NOs in bold caps.
T'Pel put Kathryn Janeway's name at the top of the list that she gave her husband.
(Because Vulcans are often seen as racist bigots, I can understand how instead of the name of a person is put on this list, that some Vulcans may deicide to rule out entire species are sexual possibilities for Pon Farr surrogacy instead.)