The volume Macintosh HD could not be verified completely

I recommend that you do this:

Repair the Drive for El Capitan or Sierra

1. Restart the computer and after the chime hold down the Command and R keys until the Utility Menu appears.
2. Select Disk Utility and press the Continue button.
3. Then select the indented (usually, Macintosh HD) volume entry from the the side list.
4. Click on the First Aid tab in the toolbar and wait for the Done button to activate. Click on it, then quit Disk Utility.
5. Select Restart from the Apple menu.
6. Download and Install macOS Sierra 10.12.2 Combo Update.

If the above cannot fix the problem, then the drive may need replacing. Make an appointment at the Apple Genius Bar for service. If needed find an Apple Store - Find a Store - Apple.

The first error simply lets you know that you need to re-download from the Purchases page of Mac App Store.

Select the grayed out entry, then click on the First Aid icon in the toolbar. Repair the disk. Does this work for you? You might consider either reinstalling OS X or doing an Erase and Install:

Reinstall El Capitan or Sierra Without Erasing Drive

Please be sure you back up if you can.

1. Restart the computer. Immediately after the chime hold down the Command and R keys until the Utility Menu appears.
2. Select Disk Utility and click on the Continue button.
3. Select the indented (usually, Macintosh HD) volume entry from the side list.
4. Click on the First Aid icon in the toolbar. Wait until the Done button activates, then click on it.
5. If First Aid fails or returns errors let us know what they are. If it reports the drive cannot be repaired or returns a failed I/O error, that usually means the drive should be replaced. Do not proceed.
6. Quit Disk Utility and return to the Utility Menu.
7. Select Install OS X and click on the Continue button.

Install El Capitan or Sierra from Scratch

Backup if possible before continuing.

1. Restart the computer. Immediately after the chime hold down the CommandandRkeys until the Apple logo appears. When the Utility Menu appears:
2. Select Disk Utility from the Utility Menu and click on Continue button.
3. When Disk Utility loads select the volume (indented entry, usually Macintosh HD) from the Device list.
4. Click on the Erase icon in Disk Utility's main window. A panel will drop down.
5. Set the Format type to Mac OS Extended (Journaled.)
6. Click on the Apply button, then wait for the Done button to activate and click on it.
7. Quit Disk Utility and return to the Utility Menu.
8. Select Reinstall OS X and click on the Continue button.

Also, see this User Tip: Basic Steps for Upgrading OS X.

... every other time I would just boot in Recovery mode, repair the disks and I could login again,

Any need to "repair" a volume should be immediately followed by creating a backup, assuming that you have not already been doing that. Whatever caused it to become corrupted is likely to occur again, perhaps in a very short period of time.

Can you start your Mac in "Safe Mode" and log in? To do that please read the instructions described in Try safe mode if your Mac doesn't finish starting up.

It's time to book a Genius appointment for a hardware test at your local Apple Store.

I imagine that you'll need the hard drive replaced 😟. It'll probably still be under warranty 🙂.

C.

Yes, if that is the one in it.