“Thinking pattern” changes once u find the one? (Marriage/serious relationship) is this true?

I am trying to understand what are the changes people saw in themselves once they were ready to settle with someone. Like i had my friends come and tell me that I was that hyperactive , Flash kinda person , Quick on jokes and more lively kinda person. Now I am more calm, “mind my own business” kinda person. Like i go – do my shit and come back. Earlier I could tell by eyes and face expression what the other person is going to say and now I have toned down a lot on assumptions (idc much tbh now) . Does anyone relates to this or is it just me kinda problem? What can be a remedy for that is this is a problem? Idk ?!?