Did your relationship really change after marriage?-

My SO and I are coming up on our 4 year anniversary, and I really can't see us getting married changing what we have now. Because like, 4 years is a really long time. We know each other really well, we've lived together 2 and 1/2 years (almost 3). We have the same life goals, we've had big and small arguments but we've grown from them and learned from them. We've had sex since like 4 months together, so I already feel like we're married because of the comfortable/grossness aspect (i.e. him seeing period blood, farting, seeing him pee, pooping, etc.)

I just mean, they say your relationship changes after marriage, and at this point I don't really think it could in a negative way. Thoughts/experience?