Was there ever a saint who, while living, convinced his or her spouse to enter religious life?
I'm certain the answer is yes, as I've seen such biographies in "lives of the saints" volumes. Saint Waldetrudis (d.686-688) and her husband Saint Vincent most likely fit your criteria. This is from Catholic Exchange:
Their home was a place of sanctity. Waldetrudis and Maldegaire [Vincent] had four children, one of whom died young, either soon after birth or before he reached his seventh birthday, while the other three grew up and entered the religious life (their son, St. Landric, may have even been consecrated a bishop). Waldetrudis and Maldegaire used their riches to help the poor; the couple was well known for their charity and piety long before entering the religious life.
Once their children had left the home, the pious parents likewise entered the religious life. Some sources indicate that Waldetrudis urged her husband to embrace monasticism, though he likely considered it prior to her influence.
Here are a couple of other cases that you might count as examples:
Jacopone da Todi -- Not canonized, but venerated among Franciscans. He was a worldly and greedy man, and his young wife secretly did penance for his sins. When she died in an accident, he discovered that she had been wearing a hairshirt. Her secret sacrifice for him motivated his conversion and eventual entry into the Fransiscans.
Saint Cunegunda, Empress and wife of Holy Roman Emperor, Saint Henry II. She had taken a vow of virginity and convinced Henry to make a vow of celibacy as well. They are both saints.
St. Conrad of Piacenza and his wife Eufrosina entered religious life after making amends for having a fire started that accidentally burned down a forest and then blaming someone else for it.
Elliott, Spiritual Marriage: Sexual Abstinence in Medieval Wedlock appendix 7 lists several couples who separated in order to enter religious life: