As with all human emotions, they are firstly human and therefore mean different things to different people. There are people who meet only one time in their life the great love, there are others who meeet several people who give them the great love emotion.
For some it is impossible to forget a lost great love, it is a memeory that detracts from any other realtionship, as it compares your lost love to you new. For others the pain of a lost love slowly melts away and they are later able to find or see another love as they are not blinded by their previous great love.
Love can be lost and found again, it can also be lost and never found again, it depends how we all look at live and love to whether we are able to love again.