You said you want to be confident in your decision to marry before you do (paraphrasing a bit) - the other poster is saying that after a couple of decades it’s possible for you to change your mind about any decision no matter how confident you were at the time you made it.
As they did when they made it at a guess. Seems like fairly straightforward English.
Seems like quite confusing English (I still don’t get it).
You said you want to be confident in your decision to marry before you do (paraphrasing a bit) - the other poster is saying that after a couple of decades it’s possible for you to change your mind about any decision no matter how confident you were at the time you made it.