Does a vagina get looser each year from having sex?

Not necessarily. The vagina is a tubular shaped muscle that is designed to stretch but return to its normal length as long as there are no tears in the muscle with activity. Insertion of large items can stretch the muscles and create small tears under the skin that arent seen but dont heel properly and results in permanent change in the size. That is why babies heads tend to enlarge the area. Exercise can help.