The answer is: Didn't want to spoil inheritance

Ruth 4:5-6

In the book of Ruth, we encounter a compelling drama of loyalty, love, and legalistic stumbling blocks. The “kinsman-redeemer” bit comes from an ancient Hebrew practice intended to preserve family lineage and inheritance (Deuteronomy 25:5-10 will illuminate this). Ruth can be seen as the embodiment of commitment and fidelity, despite facing societal challenges as a Moabite widow.

So, why is this nameless kinsman hesitant to marry Ruth? It all boils down to a practical conundrum: he believes that the redemption of Ruth will complicate his own inheritance. He is worried that marrying Ruth could dilute his estate and pass on that inheritance to a son born of her - not his biological child! Such caution reflects the realities of tribal land ownership and the potential loss inherent in commitment.

Now, isn’t it fascinating how love often triumphs over law? Boaz, portrayed as the true hero, seizes the chance to marry Ruth and defies societal expectations. But let’s not forget the symbolism here: Ruth, a foreigner, becomes part of the lineage leading to King David! It's a narrative where laws meant to bind end up sanctifying an unexpected grace – paving the way for a bigger story.

Fun tidbit—Ruth becomes great-grandmother to David; from Moab to the monarchy, proving that love and faith stretch even beyond borders and conventions!