Is it really normal

Is it really normal for friends to talk about their friend's previous relationship at that kind of event, without considering that the current girlfriend or boyfriend might hear them? I've never been in a romantic relationship, but so far, within my circle of friends, I've never heard them talk about a friend's past relationship when the current partner is present. Why would they need to bring up that kind of topic there? Maybe they could talk about it at another time or in a different place. Hope they both fix this issue right away. :((.