And it is permanent, no undo button. Our own alternative universes are found in the thought processes given to those decisions.
One of the ugliest truths about life is, every choice we make kills another version of ourselves. Get married, and you'll eventually miss the freedom you had alone. Stay single, and there will be nights when you wonder what it would've been like to build a life with someone. Have children, and you'll miss parts of the life you never had before them. Don't have children, and you may spend years wondering about the family you never created.
There is no perfect path and there is no decision that leaves you with everything.
The life you didn't choose will always look better from a distance because you never had to pay its price.
Stop searching for a choice you won't regret, it doesn't exist. choose your life, accept what it costs, and live with the consequences.