Severe pain preventing penetration often points to conditions like vaginismus (involuntary pelvic muscle tightening) or dyspareunia. While local anaesthetics (like 2% lidocaine gel) can reduce discomfort, they can also numb your partner and mask potential tissue damage. Oral muscle relaxants are not recommended or effective for this condition. Please avoid self-medicating, as it can be unsafe. I strongly recommend that your wife consult a gynaecologist or pelvic floor physical therapist. They can safely diagnose the root cause and provide highly effective, targeted treatments, such as pelvic floor therapy or vaginal dilators, to address the issue comfortably and safely.