Inspired by a comment in Why did Amanda Grayson marry Sarek?
I was wondering if there's a canon or even expanded universe reason that indicates why, (after the death of his first wife) Sarek would marry another human?
There's no "in-canon" description of why Sarek would have married another human (e.g. as opposed to another Vulcan) but we can certainly speculate on some possible reasons;
It's certainly possible that this was a sufficiently shocking event in Vulcan high-society as to prevent him from securing another Vulcan wife of appropriate standing. Since humans have no place in the Vulcan aristocracy, there's no shame incurred in his marrying an outsider.
He describes his marriage to Amanda as "logical", especially given his position as Ambassador to Earth. As a Federation Ambassador, it would also make good sense to have a human wife since humans seem to be an important and influential group in the UFP.
Vulcans often go for years between sex acts, supplementing time apart with prayer and meditation and only indulging in sexual acts, when together, very sparingly. Only having sex once or twice a year would probably be frustratingly rare for a newly-wed human woman and it's very possible that his sexual appetites may have changed after spending time with his first wife. I can see him becoming used to having (ahem) relations substantially more often than would be normal for a Vulcan male. A Vulcan woman would see this as gross perversion whereas a human woman would be far more understanding.
Sarek has known for many years that he's at risk of Bendii Syndrome. Since this manifests in outbursts of emotionality, caring for him would be an amazingly difficult task for a Vulcan woman. By comparison, a human would view his actions as relatively routine.
Within the EU canon, the TOS Comic : Enter the Wolves describes his courtship of Perrin Landover. The details bear a remarkable similarity to his courtship of Amanda Grayson;
"Perrin was a xeno-linguist, who had met Vulcan Ambassador Sarek at a diplomatic circa 2326. She had asked for and was granted an interview with the ambassador, and the two met regularly during the following year. Sarek surprised her by opening up about his loneliness following the death of his wife, Amanda Grayson, and eventually asked her to share his life."
Sarek married Perrin cos once you go Terran you don't go back lol Seriously he married her because he loved her, he confessed as much via Picard in the episode 'Sarek'. Also according to Tuvok the Vulcan male libido increases with age perhaps only a Human can keep up with them lol. (Vulcans can have sex whenever they want not just every 7 years)
Did anyone ever think that he married another human because of Spock? That it would be easier on him that his stepmother was of Earth and therefore relate to him better? Geez people....