There were at least two books with the same world design. In the far future space travel became possible and a number of planets were colonized by people interested in preserving or recreating old earth cultures or creating a society based on someone's fantasy. One such planet was (??), where the society's design was sort of based on French culture of the 3 Musketeers era - sword duels, honor above all, etc. As I recall, faster than light travel had been discovered after these worlds were colonized, and the shock of becoming reconnected with the rest of humanity led some planets to self-destruct. (Some of the colonized planets had gotten rid of all memory of where they came from.)
On the planet described above, a young man who is nonetheless too old to still be having swordfights over women is recruited by the organization tasked with keeping planets from self-destruction when they are re-contacted. He is sent to a puritanical ice planet first, where he meets a young woman who he falls in love with and subsequently marries (in later books?) in spite of the fact that he doesn't find her conventionally attractive.
In a subsequent book he is sent to a planet (or solar system?) where 2 different cultures were seeded, and they are on the verge of mutual annihilation. One culture is based on Aztec (or Inca or Mayan?) culture; I don't remember what the other is based on, but I remember they had underground parks with water features to escape from the intense heat of day.
I seem to remember the protagonist's name being something like Girault, and his wife's name being Margaret (perhaps with a different spelling?). In the later book(s) their marriage is on the rocks, which is one of the things that made the book interesting to me.
At the beginning of the first book one of the protagonist's friends is killed in a duel. Because this does happen every once in a while, the young people on his planet make frequent psionic (?) recordings of themselves and if they die their recording is attached via a device to a friend. In this case the friend's personality isn't well suited to this, and he eventually loses cohesion (I don't remember the terminology).
The basic setup is very similar to Harry Harrison's "Planet of the Damned", which I just read, and I would suspect "Planet of the Damned" was the inspiration for it, but the books I'm looking for don't seem to be written by Harry Harrison.
These books are probably at least 30 years old. Any help? Thanks!