I feel that the relationship is very unbalanced.
David is a faithful and honest husband and father, he only loves his wife and does not consider cheating, perhaps he is uncommunicative, does not attend to the needs of his wife and is very, very innocent. His only problems come at work due to a bad move by his father that is putting him in a stressful situation. He trusts too much in "friends" who are not friends and who continually tries to sabotage him without being able to put them in his place. But Anna plays a fundamental role there, as she is not being honest with her and hides many things from her, especially her indecent flirtation with Chris.
And Anna, oh Anna, has many miles behind her, her college boyfriends, that high repressed sexuality that overflows her, wanting on the one hand to be an excellent worker, loving wife and dedicated mother and on the other that bitch who is dying for a good fuck.
Unlike David, Anna is not honest, she is not sincere, she does not know how to set limits (or she continually breaks them), she gets carried away a lot by the opinions of others and somehow allows all the guys around her to manipulate and harass her. She begins to accumulate too many corpses in her closet.
Despite the image that she wants to convey as a tough and confident woman, she is tremendously naive and completely trusts people who sabotaged her two years ago, to the point that Kendra's influence is an important asset to question the loyalty of the her husband.
She believes herself to be a liberated woman who knows how to cut through bad situations when the reality is that they continually overwhelm her. And when she receives the blow of "evidence" that incriminates her husband at no time does she give him a choice, she trusts more in the testimonies of unknown people than in the person she promised to trust and love forever.
Anna is the weak link in the couple, she is aware of the excitement she provokes and she believes she can manage it but she continually proves that she is not.