‘ And they took for themselves wives of the women of Moab, the name of the one was Orpah, and the name of the other Ruth, and they dwelt there about ten years.'
But gradually the sons would grow up, and it was at that point that they took Midianite wives for themselves. These were named Orpah and Ruth. There is no certainty as to the significance of the names, which would be Moabite names. While there appears to have been good relations between Israel and Moab at the time, their taking of foreign wives might well have been seen by many as a downward step, a consequence of Elimelech's initial mistake. Compare how associating with surrounding nations is disapproved of in Judges 1, although admittedly there it was because they were Canaanites. But the Moabites were disapproved of almost as much, as Deuteronomy 23:1 ff makes clear. And then ‘about ten years' passed by while they continued to dwell among the Moabites. ‘Ten' regularly means ‘a good number'. There may be a hint in this that they remained there overlong. That may have been seen as the reason why the sons also died.
We note that during those ten years neither son had fathered an heir. Both marriages were barren, a further sign of YHWH's disapproval. It would have been seen as signifying YHWH's disapproval of their presence in Moab. And it meant that Orpah and Ruth had no one to act as their protector in the future. They shared in Naomi's desolation, three poor women with no male protector.