Long term relationshippers… how do you REALLY feel when you’re with “The One” after the initial dating phase?

Everyone talks about finding the one, but as someone who hasn’t yet found the one, and is thinking their current one might be the one, I want to know what you all think. I don’t have many people IRL who are in healthy or long term relationships to use as examples of what good looks like, so naturally I’m coming to you, oh brilliant people of Reddit!