Naomi did not return to Bethlehem because she had nothing to live for in Moab. She returned home when she found out that the Israelites were no longer suffering from the famine. Naomi was chasing ways to absolve her physical hunger. At times her spiritual immaturity contrasts with the loyalty and steadfastness shown by her Moabite daughter-in-law. Naomi grew up among stories of the wonderful deeds of the Lord. However the way she and her family lived their life seems to be fickle in contrast to Ruth's steadfast devotion.
Ruth 1:6 Then she arose with her daughters in law, that she might return from the country of Moab: for she had heard in the country of Moab how that the LORD had visited his people in giving them bread.
When Ruth and Naomi came to Bethlehem it was the time for the Barley harvest. It is important to notice that they are returning to the land that Naomi left because of famine only to lose several important things in their lives and come back to find a harvest.
Let us list some of the losses that Naomi suffered in Moab:
She lost her national identity as an Israelite. She was a sojourner, a refugee in the land. As a result she was deprived of the pride of being the chosen people of God.She lost her home. The tribes of Israel were all given an inheritance in the land of Canaan which was to be their home. Naomi's home was Bethlehem. When she left the land she lost her true home.Naomi lost her husband. When Elimelech died in Moab, Naomi wasn't only widowed. She was left without a guardian. She had no kinsman redeemer and in the patriarchal home, her immediate guardians became her two sons.Naomi lost her sons Mahlon and Chilion. In a land obsessed with offsprings and inheritance Naomi became childless with no hope of future children at her age, especially without a husband.
However for Ruth it is different. On coming to Israel Ruth stands to lose a lot many things. Remember that this is the land where bloodline is very important and someone not born of Abraham is seen as a second class citizen in the least. Their own law states that such a family would not be deemed pure for ten generation. Ruth knew that she would be treated with contempt in Israel, if not from all then from some. She was mentally prepared for that.
Ruth, who we learn was quite a young woman did not stand much chance of a home and a family in Israel. No one was likely to want a foregner and a widow for a wife, knowing that her first born would bear the name of her dead husband. If she remained in Moab, among her people, she had a better chance of securing a husband and a home. That is what Naomi was pushing her towards. That is what Orpah settled for.
Ruth was a Moabite, married in the land of Moab. It is not fantastic to assume that she was surrounded by her kinsman and family from her father's side. That was not so in Israel. The only one she would have in Israel was a bitter and mourning mother-in-law.
As two widows, the chances of Naomi and Ruth being well fed or well off is impossible in the patriarchal world of ancient Israel where women are parcelled off with a piece of land. Ruth did not even have any hope of material comfort even when there seemed to be food in Israel. Without an earning member whatever Ruth could earn was through the grace and favour of those around her.
Ruth had more reasons not to go to Bethlehem than Naomi had to go to Moab. The one thing that kept her going was her loyalty to her deceased husband and his family. Mahlon is not mentioned many times in the book but his presence is a guiding factor to the narrative. We know little about him except his family but we know that his widow makes a vow to his family after his death that is till this day regarded as a wedding vow.
Ruth 1:16-17 And Ruth said, Intreat me not to leave thee, or to return from following after thee: for whither thou goest, I will go; and where thou lodgest, I will lodge: thy people shall be my people, and thy God my God: Where thou diest, will I die, and there will I be buried: the LORD do so to me, and more also, if ought but death part thee and me.
When Ruth arrived it is the time of the harvest and in that she finds food by gleaning the ears of corn that are left behind after reaping. It was a custom of the Israelite to not go back for the ears that was missed during harvest to feed the widow and the travellers. Ruth was both.
Lev 23:22 And when ye reap the harvest of your land, thou shalt not make clean riddance of the corners of thy field when thou reapest, neither shalt thou gather any gleaning of thy harvest: thou shalt leave them unto the poor, and to the stranger: I am the LORD your God.
We see that when Naomi chose to walk out of God's covenant, in search of food, she lost everything. When Ruth decided to walk in the covenant of God, though the covenant was not hers to claim, by marriage she took part in the promise of God.
Though the book of Ruth talks about widowhood a lot, the book is mostly about marriage. The harvest is an important symbolism in that context as marriage is inexplicably linked with fertility and furthering the family line. Ruth was faithful in her marriage which was short lived. The God of second chances, therefore offered her a second chance at marriage.