It's rude to antagonize an ex.
Hal sees his ex girlfriend Dana at work and Dana asks how Hal is doing.
Hal wants to respond to Dana.
Hal tells Dana he is doing fine and asks how she is doing.
Hal tells Dana that the girl he is dating now is an improvement.
Dana will tell others at work that Hal is polite and it's a pity they did not work out together.
Dana will tell others at work that Hal is spiteful and crass.