29-sai no Fu Junai

Kiyo Hori (age 29) married Mitsuhiro Yoshida in four months after a serious heartbreak with Yasutaka Mizuki, a married man who was her senior at work. Mitsuhiro is a divorcee. The divorce was caused by infidelity on the part of his ex-wife, Reina. She married Mitsuhiro, who paid monthly child-support payments to his 3-year-old who lived apart from them.... Kiyo, though, found her marriage to Mitsuhiro to be better than she had imagined. Mitsuhiro's passionate courtship led to marriage, which led to a comfortable life and perfect physical chemistry between the two. If only it weren't for the frequent interference from Reina, who uses her and Mistuhiro's child as a pretext to disturb the peace......! How many more intrusive phone calls to her husband can Kiyo take before she confronts the situation?!?!

(Source: MangaPlaza)