How does this even work?

I’ve never had a long term relationship and now that I’m finally in one, I don’t understand how it works? I know a few things have changed since we first started talking, for example: 1) no more good morning texts 2) they don’t tell me when they’re making plans- they’ll let me know the day of that they’re going somewhere 3) sometimes they’ll not message for an hour and say they were caught up 4) late replies 5) no messages when out with friends Now I’m not sure if I’m being crazy but should I be worried? I just don’t understand why these changes are happening