Will the husband be sinful if he divorces his wife after he has deflowered her, because he does not feel happy and stable with her, due to the frequent disputes between them, and his desire for a wife who is more religious, modest, and committed?

If the situation is as you described, then there is no harm in divorcing one's wife due to her bad character and the husband's suffering from it, as it is permissible when needed. However, it is preferable to be patient and strive to reform her and obligate her to perform her duties and prevent her from evil deeds, in accordance with the man's guardianship (qawamah). He should also prevent her from leaving the house except with his permission and while properly veiled with the legal hijab, and from suspicious mixing with men at work. If she does not obey the husband, he should follow gradual methods of reform with her: admonition, then abandonment, then non-injurious beating. If this does not help, then divorce is the last resort.