What is the reason for a husband abstaining from his wife for more than a year and a half, not having intercourse with her or spending on her, and should the wife seek divorce or be patient?

If the husband is "tied" (impotent and unable to have intercourse), it is preferable for the wife to be patient and ask him to continue treatment or ruqyah (Islamic exorcism/healing), or to perform ruqyah on himself. If he does not respond, she may request a divorce. If he does not divorce her, she takes her case to court, which grants him a grace period of one year. If he has intercourse with her during this period, then good; otherwise, her right to choose separation through an irrevocable divorce is established. He must provide for her appropriately; otherwise, that would be another justification for her to seek a divorce.