alien invasion novels

It would be better if he stayed at home that day…
A regular guy went fishing and suddenly met a beautiful but unusual creature who needed love and earthly sex. A monster in the guise of a beautiful woman? Scared, he ran away and tried to forget… But suddenly this beautiful creature became a part of his life when he saw somebody trying to kill it. He hurried to save it, but where is it now?
It is a love story without a definite happy end. They are too different. Why does he need monster love? How can they be together?