Intimacy is meant to reveal hidden layers of love that are not readily available alone. The use of pornography is to satiate sexual desires. This is quite easily justified within our culture, as immediate gratification is a popular way of living. The psychological piece that is mostly overlooked is how pornography influences our choices and how we interact with the world.
To argue against this, would be the same as arguing that advertising doesn’t work. To truly seek intimacy, we must reveal ourselves to the other person. When we watch pornography, we are bringing other people into the conversation.