Keep in mind this was 1979 when all sorts of guys were screwing underage teenage girls, from Roman Polanski to David and Angie Bowie to Steve Tyler to Jimmy Page, 13-14 year old girls were all the rage. And 15-17 year olds? Well that was just normal.
But people were still going down in this stuff back then. The charge was called “statutory rape” and it was the subject of a lot of jailbait jokes. Depending on your age, you could go down. A 21 year old man could do some short stretches, harassment meant to teach a lesson. A 53 year old man having repeated sex with several 15 year old girls might be looking at three years in prison. There was no Sex Offender Registry and not one sane person thought screwing a teenage girl was child molesting or pedophilia. Instead teenage girls were regarded as dangerous vixens. For a man to have sex with them was regarded as a normal but dangerous temptation that wise men avoided for fear of a few weeks to a few years in the Graybar Hotel.
For men my in my cohort age 24+, I figure 94% of us managed to avoid underage girls. There were a few guys swimming with the girl sharks, but it was probably only ~6%. Things were not as depraved as you think.
Feminism was unpopular then so there was no Pedophile Mass Hysteria. Most people figured that most men would probably like to boff an underage teenage girl, but the idea was you should just say no for fear of possible arrest. It was more of a legal question than a moral or psychiatric one.
Men, especially Black men, were regularly arrested on these charges. In my all-White town, I knew two Black men who got in trouble for having sex with 15 year old White girls. One was my teacher, Mr. Matthews. He got fired, but at least he didn’t go to jail. Another one was my adult friend M. D., a former football player built like an ox.