Money Trap Honey
Elke Sommer in The Money Trap (1965), available from the Warner Archive. Forty-nine year old Glenn Ford plays a detective. He's married to 25-year-old Elke Sommer, but he meets an old flame played by 47-year-old Rita Hayworth. Forty-five-year-old Ricardo Montalban plays Glenn's partner. Sixty-year-old Joseph Cotten plays a bad guy. So, basically, the hero has a wife half his age, and his "old" girlfriend (who is two years younger than he) is a "washed up" waitress. Hollywoood can be so cruel at times.
Here is a YouTube version.