Her job was to open her mouth, his job was to keep it closed.
Never confirmed any illicit student-teacher relationships during my days in high school 40 years ago. Our female teachers (as a group) were very unattractive and if they were on the prowl, I don't imagine they had very much luck. Same held true for 99% of our male teachers. Apparently, they didn't want to risk their careers on a fling with a student.
The exception was our drama instructor, who was relatively young and his female students found him very attractive. Lots of rumors about him boinking cute girls who were in the drama club and it was not surprise that many of them wound up being cast in school productions. Don't recall his office having a casting couch; I can only assume the auditions were held elsewhere. The same teacher also made it a point to fawn over the kids of school board members and other important officials. After being a struggling actor in New York for a few years, he wasn't about to do anything to jeopardize his new-found security.
Whatever his modus operandi, it worked. He got tenure, taught in the local school system for 30 years and retired. And, for a small, rural district, the drama department never seemed to lack for funding. I did hear about one former student who named her son after him, but that was supposedly a “tribute” to her favorite teacher and not an indication of parentage (nod, nod, wink, wink).