That happens to me with the games I like mainly from rpgs and life sim games. Take a break and come back when you really feel like it, otherwise the burnout will get worse if you force yourself to play when you are burnt out. Another thing, playing too much can make you feel more burnt out on a game.
Same. I feel that way with every game but Animal Crossing especially. Some days you feel addicted. Other days you're just not in the mood. My breaks grow from months to years though because of how many times I've played some of them games, New Leaf especially.
One thing you could try though is coming up with more ideas like for designs or paths and such. I don't consider myself nearly as creative as a lot of people on this site, but every now and then I do get good ideas or make patterns/paths that end up looking really well. That certainly gets me playing. Unfortunely I do get that burnout and leave a lot of stuff unfinished because I end up not caring anymore, but I guess it'll wait for another time when I'm in the Animal Crossing mood again.
I get burned out a lot playing animals crossing. I usually put the game down for a while, whether it be few hours or a few months, and go look at smth else. I sometimes go to reddit to find out trivia or other such things about the game to get me back interested in it.
As someone who played New Horizons every single day for an entire year after release, I've been burnt out plenty of times since then. I came up with some tactics to try and extend my playtime so that I don't get sick of the game as easily, as the whole purpose of the series in general is to get you to come back on a semi-daily basis. I'll also share some things that I haven't tried personally, but know have worked for others:
Obviously the biggest piece of advice I can give someone is DO NOT TIME TRAVEL! You will enjoy the game much more if you play it as intended. I have never time traveled on my main island, Wahu, and I was able to get much more enjoyment out of simply building it up on a day-by-day basis, and forcing myself to wait until tomorrow for buildings to get moved and bridges/inclines to be built. Yes, it can be tedious to have to wait, but it pays off.
As much as you want to keep accomplishing goals, don't play the game for extended time periods in one sitting. Villagers will even remind you of this in New Leaf (somewhat of a fourth wall break), but not in New Horizons. For instance, if you're decorating outdoors on your island, only work on one small section a day. Trying to do half the island for an entire day will only cause fatigue that will influence you to not play again for a while. In general, if you start feeling sluggish and tired when playing, it's a sign that you may need to stop your play session. For the average player, over an hour of continuous playtime is usually too much after achieving a 5-star town.
If there's a specific goal you're trying to achieve, such as capturing a specific fish, don't try to get it in one sitting if you keep failing. It only causes frustration. The exception I'll make is if the creature goes out-of-season in a day or two. I mean, who else wants to wait an entire year for salmon to return?
Not everyone likes to do this, but cycle your villagers if you can. If you have a "dreamie" on your island that you do not want to get rid of, then keep them. If you don't feel as strongly about other villagers, let them move away after a couple months. Just keep in mind that if you want their picture, then you may have to keep them for extended periods of time. Yes, dialogue will repeat itself after a while, but at least some villagers in New Horizons will perform different hobbies.
I will also mention that New Horizons had much more replayability and things to look forward to back when updates were still being rolled out. Does this mean that you won't enjoy it as much if you were to start playing today? I'd say no. Despite the game now being past its popularity peak, there are more things you can start doing immediately compared to when it first released. There are still players who want to visit islands online as of this post, so don't fret if that's a concern you're worried about.
