My boyfriend complains so much. It’s in a fussy almost child-like sort of way. I swear he wasn’t like this before and this is a new “thing” that came

I absolutely hate it when people are like that... even though I'm kinda like that myself tbh. Maybe see if there's some deeper issue he hasn't been addressing that's been putting him in a shit mood? IDK, that's all I got. Barring that, I think it's pretty reasonable to address him about it, like "honey i need you to chillax a bit about shit that doesn't matter"

Relatable.... Only thing that stopped it was to cage myself or drop her ass.. However, I suppose you could tell him if he can't focus on the important things of life then it ain't gonna wooooooooooooooork.... Maybe... My 2 cents anyway.. ┴┬┴┤•ᴥ •ʔ/

Start by listening.
Keep listening until he stops talking of his own accord.
Then try to reflect back to him what he said, and check with him whether you've understood it correctly.
See if you can figure out if he has a particular underlying need.

Now check in with yourself. Are you able to meet his needs?
And if so, is it something you can do without inconvenience to yourself? Is is something you would like to do?

If you can't, tell him so, and tell him why.

And then look for alternatives that will meet his needs without compromising yours.

(P.S. maybe double check whether he's showing signs of being a control freak. If he is, that "fussiness" is a sign to get out now before things get worse.)

Call him out on it

Give him a hug

Ask him if he misses his momma whinning like that, and that your not his momma and needs to stop that crap.

Talk to him! This is only way! He can only do something!

Trade him in for a Honda.

Ohhh I deal with this a bit too. I dunno some people are fussy. He's gotten comfortable with you and he's no longer on his best behavior.
Tell him. Dont nag him about it but just tell him to not sweat the small stuff so much because you prefer a less stressed out life.
Tell him that he can only complain once a day so choose wisely.
If he's complaining more than once daily maybe the relationship isn't working out.

He's showing his true colors now. You had better take heed. For your sake. 🙂

Send him to his room