No, you can entertain independent thought without ever sharing it with your social bonds.

"It seems that changing your mind about something could risk divorce or losing your friends."

I change my mind about things all the time and talk to my wife and friends about it with no issues.

If you are talking about politics, find a new wife and friends.

No. You are still your own independent person, even in a marriage. If your bonds of friendship are merely the result of you holding the same opinions, then you are not so much friends as you are common-goal acquaintances, such as two strangers meeting at a sports event where they are both rooting for the same team. If a change in your opinion is grounds for no longer being friends, such as the same strangers meeting at a sports event and realizing one of them "defected" to root for the other team, then it is clear you as a person had little to do with the friendship and it was more about convenience or selection bias.

With this in mind, most "friendships" on social media are driven by the ideas you align with, and it is a reason why the old idea of "cancel culture" can be subject to such whiplash. If you are only friends, followers, or mutuals with people who believe the same ideas as you, one of them expressing an idea you did not think they would have might lead you to distrust them - even though you don't know them as a person at all, but a "collection of ideas" you agree with.