Felix was a medical doctor, Jesuit-educated, no longer a faith believer, but he promised he would never interfere with her practice of the Catholic religion. Elisabeth was an attractive, good-natured, and intellectually curious lover of the arts. She had mastered Latin, English, and Russian. As a couple this was one that seemed to "have it all." However, very early in the marriage a massive failure of communication seemed to be ready to topple the union. Felix became an atheist, and made great efforts to evangelize his wife. For a time his efforts seemed to bear the fruit he wanted, but suddenly his efforts backfired when Elisabeth came to see the poverty of his thought.

Elisabeth’s re-education in the faith came about through her study of the New Testament and the lives of the saints. The efforts of Felix seemed to ground her more firmly in the faith. He noticed that her faith became more radiant and unshakeable; her path to God was on a firm basis even as her suffering intensified. The main sources of Elisabeth’s suffering were the tension between husband and wife over the issue of religion; the ridicule and mockery Felix and his atheistic friends gave her; her inability to bear children; and the lack of support in her works of mercy. She was also afflicted with several physical ills even though her husband was a physician. He did accompany her on a trip to Lourdes and was amazed at the relief from suffering that many experienced.

Elisabeth had an uncanny ability to make use of suffering for the benefit of those who inflicted it on her. In prayer she asked God to "give me one day soon the immense joy of full spiritual communion with my dear husband, of the same faith, and for him as for me, of a life turned toward Thee. I will redouble my prayers for this intention; more than ever will I supplicate, suffer, and offer to God Communions and sacrifice to obtain this greatly desired grace." (One can only imagine the feelings of Felix when he read this prayer in her diary after her death.) "I want to love with a special love those whose birth or religion or ideas separate them from me; it is those whom I must try to understand and who need me to give them a little of what God has placed within me." Her goals were to understand those who are so different from herself, who took delight in abusing what she loved; and secondly to love these same souls.

The spiritual well being of her husband obsessed her and she never ceased praying for his conversion. However, she knew that deliberate efforts to bring about his conversion would be doomed to failure. She was convinced that a positive change in Felix was strictly God’s work. She rejoiced that shortly before her death he stopped his hostilities, as he could no longer ignore her growth in sanctity. Elisabeth died of cancer in 1914. Felix marvelled that peoples of all ranks came for her funeral. "A revolution took place in my whole moral being. I understood the celestial beauty of her soul and that she had accepted all her suffering and offered it for my conversion. "

By the spring of 1915, the conversion of Felix was complete; he began going to daily Mass, reading the Gospels, and became a Dominican Tertiary. He was given the task of beginning the process of Elisabeth’s beatification. In the fall of 1919 Felix became a Dominican novice, and was ordained to the priesthood at the age of 62. Married for 25 years, his priesthood would cover a span of 27 years. Father Felix Leseur died in 1950 after several years of hospitalization. When an inventory of his room was made, there was only his breviary and his rosary.