Sildenafil (the active ingredient in your medication) is generally safe for long-term use under medical supervision. Common side effects include headaches, flushing, indigestion, and nasal congestion. Since your erectile dysfunction occurs only with your wife, it is likely linked to situational or psychological factors rather than physical ones. To naturally restore your desire and performance, consider couples therapy or sex counseling to improve communication and intimacy. Additionally, managing stress, exercising regularly, maintaining a balanced diet, and ensuring adequate sleep can significantly boost your sexual health. Please consult your doctor to safely manage your long-term health.