3 onsites, still no offers

Title. This is my first cycle.

I’ve had 7 zooms and 3 onsites so far since September. No rejections but 1.

I’ve left every onsite feeling like I definitely got the job. They smile and promise that I’ll hear from them soon, literally almost to the point where it seems like a verbal offer. Then nothing.

Why won’t someone just send me an offer?