The answer is: Didn't want to spoil inheritance

Ruth 4:5-6

In the story of Ruth, we find a fascinating intersection of duty and personal ambition within the customs of ancient Israel. When Boaz informs the closer relative about the right of redemption for Naomi's property, the kinsman is initially interested but quickly retracts his intentions after learning that marrying Ruth would complicate his own inheritance. This reflects not only his priorities but also the societal structure of the time, where land and ancestry held immense significance.

In that culture, marrying a widow was seen not only as a moral obligation but also as a potential threat to one’s familial inheritance. By taking Ruth as a wife, the kinsman would integrate her future offspring into his lineage, jeopardizing the preservation of his own name. It shows how complex relationships and social norms guided decisions beyond just personal feelings—Navigating family, loyalty, and legacy was an art.

Interestingly, this moment in Ruth echoes similar themes elsewhere in the Bible. The strict concerns for lineage and land-rooted heritage can also be seen in texts such as Deuteronomy 25:5-10, which are all about preserving family names and ensuring prosperity within tribes. Plus, the mention of Moabite ancestry highlights broader themes of acceptance and integration into Israel's covenant community. In the end, while the kinsman opts for self-interest, Boaz steps up with courage and love, embodying the spirit of redemption and reminding us that the value of relationships, particularly love and loyalty, can often take precedence over mere inheritance.