I'm no fan of the man. He got into the big time in the 1960s because Billy Wilder wanted a schmucky little actor to play the role of "Mr Everyday American'.
But when Lemmon got into the big time he had the power to choose attractive-looking European women to support him (This was in the days when most French actresses were regarded as "sex-kittens").
He got Romy Schneider then Virna Lisi then Catherine Deneuve.
Isn't that just a sign of the times? He must have acted opposite a lot more Americans
shareI think more they were attracted to him as a co-star as he was a massive box office star from the late 1950s onwards (especially in the mid 1960s). Actresses like Virna Lisi got her first big break by starring with Jack.
If anything I think he had a good mix of beautiful co-stars from all over the world. Marilyn Monroe (US), Juliet Mills (UK), Carol Lynley (US), Natalie Wood (US), Virna Lisi (Italy), Romy Schneider (Austria), Catherine Deneuve (France) to name but a few.