I cannot redeem it myself: Adding Ruth to the deal changed everything for the other relative.
I would jeopardize my own inheritance: If he bought the land, married Ruth, and raised an heir for Elimelech, he might invest many resources only to lose control of the new land. He might not have enough to maintain his own land. If he failed to have a second son with Ruth as his own heir, his land would go to Elimelech’s heir, and his own name would disappear. Even if this relative acquired the land without Ruth (see study notes on Ruth 3:11; 4:5), he might still lose his investment to Ruth's heir. By trying to protect his own name, this man became the nameless one who refused to help his close relative.