Can men and woman be just friends?

This topic of can men and woman just be friends has come up quite a bit lately at my work place, in the media, and on social media. I guess it's more acceptable if both parties are single, but what if one or both of those people are in relationships or married? Is it possible to be just friends with someone of the opposite sex that is in a relationship without being attracted to them? I am a single woman who has no interest in meeting up with any guy who is in a relationship because I know how jealous woman can be, so when I do get asked to meet up with a guy friend I usually include their partner. When I was married my husband did have work friends who were the opposite sex, and I will say if I thought these woman were attractive I did get a little jealous if they were getting too chummy with him.

Every relationship is personal and what works for some couples may not work for all, but I do think there should be some boundaries put in place so those boundaries are never crossed. In a non work situation meeting up with the opposite sex for whatever reason could lead into trouble down the line. I have a childhood male friend that lived across the street from my former husband and he had no problem with him coming over and spending time with me alone when we were married because we all grew up in the same neighborhood together. I think that probably wouldn't have been okay with him in a different situation. Although I do have many male acquaintances I think that at some point one of us is always interested in more than just a friendship. Do you have friends who are the opposite sex, and how is that working out for you?