Sex can be painful for the first few times. Use a lubricant before insertion. Don't force her into the act. Make her comfortable before insertion. That should probably settle the problem. Dr Sachin Dalal

Hi there I understand your concern...Involuntary spasms of the muscles of the vaginal wall...it is usually severe enough to prevent intercourse; the cause may be organic or psychogenic....If you guys are newly married nothing much to worry as it's common in new relationships...Consult nearest psychiatrist they will do the needful.