What does grey mean in "The Lady With A Dog" (i.e grey fence and hotel room)?

In "The Lady with the Pet Dog," Anton Chekhov tells the story of an adulterous affair that turns into true love. Dmitry and Anna meet and begin the affair at Yalta, a seaside resort, in full summer, where they often are outside in glorious nature. After they return to their respective homes and realize there is more to their relationship, they begin to meet clandestinely. Both realize that they are suffering because they have not faced the truth about their marriages and, more broadly, their lives.
Gray is associated with the artificial, soulless, desolate landscapes of their inauthentic existences. Anna, for example, lives in a house with a gray fence. They meet in dim, dull hotels as they try to push past the mediocrity of routine existence and live with emotional honesty.