First of all-did your rav mean greeting aquaintances or greeting absolutely never met before and never will meet people.
Does it matter? Why is a stranger different (vis-a-vis “al tarbeh…”) than Mrs. Katz, the wife of a fellow who davens in my shul?
Anyway wolf-Pleeeeeaaaasssseeee don’t act silly. You know a wife is different.
On the contrary — look at the Mishna — it goes out of it’s way to INCLUDE one’s wife. Why should one’s wife be different when the Mishna specifically includes her in “al tarbeh…?”
The Wolf