Apologies for the vagueness of the question, but I cannot for the life of me find this game again. It plays as a visual novel where you are the husband's brother and you go to stay with the wife while the husband is away on business. During the early game you walk in on wife masturbating and in general having trouble controlling her sexual urges while her husband is away and things escalate over time with you "helping", ending I believe with wife falling for you now.