Sengyou Shufu Tantei ~Watashi wa Shadow

Asagi Serina is a housewife who loves her husband, Takefumi, to the extent that she would not mind being his shadow. However, his response to her excessive devotion is to attempt to avoid her "burdensome", "gross" expression of love. With a wife's naivety, she refuses to suspect her husband of infidelity and initially gets frustrated.
One day, with the help of her good friend, Motoko, Serina goes out for a meal with the men at the publishing company where Motoko works. The moment a man in the group makes a move on her, it is captured on film by the sleuth, Jinnai Haruki. Not wanting her husband to see the photograph, Serina starts working at Jinnai's detective agency as an assistant.
This ordinary, bumbling housewife grows stronger and improves her self-confidence through the skills she hones. Serina wants to support and help her husband instead of flaunting her new self to him because he is having a hard time. Aware of the problem that happened to her husband because of her over positivity, she sets about trying to solve it.
(Source: Jdrama Weblog, DramaWiki)
~~ Adapted from the manga "I Shadow (私はシャドウ) by Kasuya Noriko (粕谷紀子).