An unchained melody moment is when you are doing something (playing guitar, watching t.v, pottery making..) with a loved one, and seems to be romanticised action.
You've all seen the film Ghost right? remember the scene when Molly (Demi Moore) is creating her clay pot and then the ghost of Sam (Patrick Swayze)comes down and helps her out? Well, the song "unchained meolody" was playing in the background...
An unchained melody moment would be something along the lines of:
*A person helps another person with his putting by standing up behind them and placing their hands on his* "woah, total unchained melody moment"
a couple drinking from the same glass through straws..."unchained melody moment"