The Girl in a Swing by Richard Adams

A shy young man meets a beautiful woman in the company of a young girl. He finds himself swept off of his feet and married to her, bringing her with him to live in his family home. She is his erotic dream come true; she does everything she can to bind him to her and join him in his comfortable life.

Soon, however, odd things begin to happen. Things in the house are strangely damp with what looks like seawater, bodies appear under the water that aren't really there. It all winds up to a horrifying conclusion.