A friend told me something very insightful yesterday in the name of a Psychiatrist named Dr. White.
"Every milestone comes along with loss".
We think that milestones are GREAT. They are. But think about it. Your baby starts to talk - you have lost that delicious period when your baby was in the goo-goo ga-ga stage. She starts to walk - you lose out on the crawling around. He is Bar Mitzvahed - your baby is growing up and you are, in a sense, losing your baby. [I am a grandfather and just yesterday my mother called me her baby...].
A person graduates. Awesome! But now he lost his fun days of being a student [if there were parts that he enjoyed], the friendships he forged in school will often fall apart etc. etc. A milestone but loss as well.
A child gets married - she leaves the home and starts a new life, separate from her parents. על כן יעזוב איש את אביו ואת אמו ודבק באשתו והיו לבשר אחד. The Torah is essentially says that there is a profound sense of loss when a child gets married. People are always "mazel toving" the parents of a new chosson or kallah but I wonder how many parents experience this sadness upon the loss [in a sense] of their child [not to mention the formidable financial expense].
And think of the loss of the child who is marrying. Until now - he was being supported and taken care of by his parents. He always had a home to go to - free of charge. No rent, no utilities. A full fridge - on the house. Now - he has to pay his rent or mortgage. Otherwise - he is homeless. Bills, bills and more bills. Life turns into bills galore. No more mommy around to pamper him [somehow, wives don't always feel as protective and nurturing toward their husbands as their mothers did]. He lost the more carefree life. Is he happy? Of course - that is why he got married. He thinks that he will be happy with this girl [sometimes he is even correct]. But there is a sense of loss.
Life is filled with milestones - and with loss.