What year did age gaps (even close gaps) become a big deal?

I know back then, there were 50 year olds dating 20 year olds. Stars in Hollywood and celebrities were fairly common with age gaps. But if that happened today, it would cause a lot of controversy. When would you say that occured?

Also I have seen people make a huge deal over close age gaps like 17 and 18 or 15 and 17 or 17 and 19