Is it permissible for a man to divorce his wife if she communicates with a strange man via telephone, and bought him a gift upon which she wrote, "I love you"?

The husband is advised to exert effort in counseling his wife and warning her against continuing her illicit relationship, explaining the unlawfulness of this act. If she repents, then all is well. But if she persists in it, then there is no harm in divorcing her; in fact, it may be recommended if he cannot prevent her, because retaining her would be a detriment to his religious commitment and a fear of her corrupting his marital bed.