With sexual relations the husband and the wife ratify the vows they made at the altar.
To pull such relations out of their context is to obscure the meaning of such expression and it is also to sin against the God who designed sexuality for His specific purpose.
This holds for EVERY age. For older persons to have sexual relations outside of marriage is to fornicate. It is a mortal sin--and nothing is worth that.
Fr. Vincent Serpa, O.P.