Final answer:
The word that fits the definition of couples getting along well and deriving from the Latin for 'to suffer' is 'compatible,' reflecting mutual endurance in relationships.
Step-by-step explanation:
The word that describes couples who get along and can live together in harmony, and which comes from the Latin for "to suffer," is compatible. This word choice reflects the idea that for two people to be truly compatible, they must be able to endure and withstand hardships together, fitting one another's needs, personalities, and lifestyles in a way that makes coexistence smooth and conducive to mutual happiness.
The origin from the Latin 'compati,' suggests a willingness to suffer together, indicating that harmonious relationships are fostered not only through joy but also the capacity to face challenges as a unit.