A Bochur once wanted to go to a mixed (seating) wedding of a relative, and asked permission from R’ Leib Lopian zt”l. R’ Leib asked him how he could go to such a place? He replied that he was going to sit separately with a sefer, and he ‘wouldn’t look’. R’ Leib smiled at him sadly: “I’m 80 years old and blind in one eye, yet I am scared every time a walk in the streets that I’ll see something I shouldn’t. You are 20, young and impressionable, and you are going to walk into a matzav of nisayon like that?”
There was a story of I think Rav Moshe, (It was an american Gadol from that time period, so I could be mistaken, but it was a well known Gadol). He was at some dinner honoring a big baal chesed. One of his talmidim came up to him and asked. “Rebbe , how can you attend an affair with mixed seating” . Rav Moshe (or whomever it was) said. The Honoree was a big Baal Chessed and warranted the Kavod of him attending the dinner honoring this person. Rav Moshe then sat next to his Rebbitzen.