Finally, men it is a good rule of thumb to introduce your wife to every woman you talk to, putting your hand on the small of your wife's back in a supportive pose so she feels safe. She loves you and feels threatened. Acknowledge it, but assure her both verbally and non-verbally that she has nothing to worry about.
And women next time you go to a meeting at your kid's school and your
husband is talking to a single mom, go over and introduce yourself to
her - you might just make a friend.