Is the feeling of intrusive thoughts (waswasa) and doubt concerning the existence of God, or the answering of prayers after marital problems, repentance, and commitment to religion, considered disbelief (kufr) or an indication of weak faith?

Praise be to Allah who has guided you to the path of righteousness. Do not rush the answer to your prayer, for Allah answers His servant as long as he does not rush. The whispers (waswas) you are experiencing are a sign of your faith, and your dislike and دفع of them are from the essence of faith, as Shaykh al-Islam Ibn Taymiyyah said. We have previously explained how to deal with waswas in previous fatwas. We advise you, along with praying for your husband's return, to pursue avenues of reconciliation between you by involving relatives or people of good will. It is a grave mistake for a woman to leave her home except in cases of necessity.