Walter Matthau? I am dubious. I can't find anything to indicate that.
https://www.scandinaviastandard.com/what-ever-happened-to-inger-stevens/#:~:text=In%20film%2C%20Stevens%20won%20leading%20roles%20in%20A,for%20pursuing%20intense%20relationships%20with%20her%20leading%20men.