Infertility due to psychological causes cannot be ruled out as there is an immense relation between the minds and bodies undergoing fertility treatment. Many women are apprehensive about the demands a child might bring into their life and hence do not want to get pregnant. The psychological factors like stress, depression, guilt, lack of self esteem etc may work in two ways.
In men it may affect their sexual abilities thus decreasing the number of times couples have contact during the fertile period. Also it may affect the hormones released from the pituitary that control sperm production.
In women, it may cause decreased sexual desire and changes in hormones secreted from the pituitary that affect ovulation.
So if you feel you need help with your infertility talk to your doctor who can refer you to a counselor.