Young men want to be faithful, and are not; old men want to be faithless, and cannot.

– Oscar Wilde

The Picture of Dorian Gray, Chapter 2. Lord Henry is not a big fan of fidelity and entertains Dorian and Basil with this rather bleak view on marriage and fidelity. When it comes to love he says it is "purely a question for physiology" and has nothing to do with your own will.