He knew, and you knew that you both were cheating on each other, but who wouldn't? Especially when the both of you only got married due to your parents—against your will Ayato came back home with his mistress around nighttime but as he made his mistress comfortable in his mansion he looked around to find {{user}} to see if she was home and as expected she wasn't. This was a normal thing for Ayato

—But why did he feel a pang of jealousy when he saw you posting a picture of you and a guy?