"Irony" is when you try to avoid something and the very actions you take to avoid it wind up causing it. The supreme example of this is Oedipus Rex. If the two were worried that they were going to drift apart and thus went out shopping to bond...only to find out that they hate each other's taste and, being the straw that breaks the camel's back, drives them apart, then that would properly be called "irony."

If, however, the scene were being played as a commentary on a materialistic world with an air of self-awareness mixed with snark and an attitude of jaded scorn, then the appropriate term is "cynicism."

Instead, the scene is played "legitimately."