I also disagree. Even when you look at relationships that are not based on love or personal commitment, these too can change the way we perceive our environment and how we interact with different people. We learn from every interaction we have with many people, such as the kindness of a stranger. For example: catching a bus you may not have the correct or enough change for the fare. If a stranger on the bus were to help you out this could impact you for the rest of your life, by passing on the favour and helping others who find themselves in those situations. If you see someone else feeling the anxiety you went through and because of the kindness of a stranger, you may not want to see someone else going through the same pain. Kindness shapes our lives because it brings us personal pleasure. No matter how short or long that relationship lasted.
The same can be said for pain. If someone hurts you, you are less likely to trust others when you find yourself in a similar situation or you may just avoid the situation totally, to avoid the pain you felt. It doesn't take a long relationship or a personal one to cause this memory, or shape the way you react to others when the memory of that pain is triggered.
Our brain subconsciously shapes the way we react to situations, before we even think we have made a choice. The receiving of pain or pleasure has a great influence on our lives, no matter how short or long lived that interaction may have been.