It Should Have Been You: said with regret to a former partner after you’ve both moved on to others but you both know you should have made it work.
I know it’s been years since we split up but ISHBY, we could have made it
It Should Have Been You: often said with regret when seeing the One that got away; especially after not having seen them in a while, and you’ve both moved on.
Babe, I know we are both now married, but I always think about you, ISHBY, my dear friend.