The Story begins with Elimelech taking his family down to Moab. In Moab he and his sons died. The sons left two childless widdows. One of these was Ruth.
On the way back to Israel Naomi told the daughter in laws to go back to Moab because they will have a hard time in Israel. This statement was Chesed. Naomi could have benefitted from having them around because they were young and could work for a living.
When Ruth decided to come with Naomi she was doing a tremendous Chesed for her mother in-law. She was not responsible for taking care of Naomi. Naomi could not supply her with any more children to marry in place of the dead sons. Still Ruth wanted to assist. At that point she accepted G-d and Judaism.
Naomi mentions the Chesed which the girls had done. According to the Targum the Chesed was that they did not want to marry gentile men but instead wanted to keep the names of their Jewish husbands alive.
Perhaps Ruth learned how to do Chesed for her husband. It can be assumed that her husband was not very observant because he married Ruth. Ruth was a gentile who did not accept Judaism until she was travelling with Naomi. Her husband was a cultured Jewish man who supported his wife did not beat her or come home drunk. She saw that this was correct way of life.
Many have said that one of the reasons for so much intermarriage is that Jews aspire to everything admirable in Society. They are educated, thoughtful and kind. Many gentiles would prefer to marry a nice Jewish boy than some gentile.
Boaz is a great benefactor in this story. After finding out that Ruth was a Maobite woman he told her that she should only collect from his field. There is a Mitzvah in the Torah to leave portions of a fields produce to the poor. There is no Mitzvah to give extra.
Boaz also told her to drink freely with the workers in the field so that she would not suffer from Thirst.
She bowed down to him thanks and said that as a foriegner she is not even suitable to be his made.
Boaz Compliments Ruth. He tells her how wonderful it is that she has come to assist her mother in-law, that she has left her land to come to a strange land where people might be mean. He blesses her by saying that G-d should watch over her since she has come under G-d’s wings.
He further tells her to cook the grains and to dip her bread in vinegar. (Vinegar was in place of butter or Techina)
Boaz then told his workers to drop extra grains for her to collect up. They should not stop her from collectin this.
By the end of the day Ruth had collected so much that she ate and was satisfied and had left over for her mother in-law.
There is another Mitzvah in the Torah called Yiboom. A brother is commanded to marry his sister in-law if his brother dies without children. This does not apply to more distant relatives.
After hearing how kind Boaz was to Ruth the whole Harvest season Naomi suggested that Ruth get fanicied up and see if Boaz might be interested in marrying Ruth.
Of course Boaz was interested and married her. Several generations later King David was born from this relationship.