A nonchalant couple.
The definition of nonchalant is not showing interest.
An example of nonchalant is the response "whatever."
without warmth or enthusiasm; showing cool lack of concern; casually indifferent
Origin of nonchalantFrench from non (L non), not + chaloir, to care for from Classical Latin calere, to be warm or ardent: see calorie
Casually unconcerned or indifferent. See Synonyms at cool.
Origin of nonchalantFrench from Old French present participle of nonchaloir to be unconcerned non- non- chaloir to cause concern to ( from Latin calēre to be warm, heat up ; see kelə-1 in Indo-European roots.)
(comparative more nonchalant, superlative most nonchalant)