I think it's bound to happen. I do wonder if poly would help. I have oak cabs also. About 11 years ago I decided to paint them white and do a crackle finish. (Hey, it was the 90's.) I did not not sand them at all and didn't even bother to clean them. I primed with Kilz, applied the crackle medium, painted one very white coat of paint, and rubbed a antiqing glaze on top. I only intended them to last a couple of years until our remodel, but here's it's been 11 years and we're just now starting. The paint chipped off of the bottom edge on the peninsula where it gets quite a bit of wear and tear. I'm sure that there have been a few other marks that just ended up blending in as they were meant to look old anyway. I dab on a little Kilz and a little white paint when I touch up. I'm shocked that they held up as well as they did for so long because I didn't prep them at all.
This new kitchen will have white painted (but not glazed or crackled!), modern looking maple cabs. I hope the finish holds up! Good luck with yours.

And to be clear, the bonding issue is at the bottom, where you want primer to adhere to wood and paint to adhere to primer. If the primer is coming off so that you see exposed wood, the primer is not bonding to the wood. NOTHING you put ON TOP of the paint film will affect the bond at the bottom, of the primer to wood. So poly on top would have no effect.

The area around the knobs can absorb a lot of oils; the skin on hands may contact the wood, and skin has its natural oils even when clean, plus any oil or grease from food prep.

I would clean the area with lacquer thinner and lots of paper towels. Wipe down, then change to a fresh towel and wipe down again. Repeat. The solvent dissolves grease, but the towels have to pull it off the surface, so you need lots of fresh towels. I would then for good measure wash with Dawn in HOT water and rinse with hot water and vinegar. (Vinegar doesn't cut grease; it's to remove any detergent residue or minerals in hard water.) Then prime with a high-adhesion primer. I like shellac-based Zinsser BIN.

thanks andersons!

i am going to follow your prep instructions.

you can see bare wood in a few areas. The paint is not really chipping, rather the paint in the area around the knobs is very soft (kind of putty like) and can be scraped away--very easily just by rolling my fingers over the area with some pressure--thus scrubbing it clean removes the paint.

other than around the knobs and the top of the drawers, the paint is perfect.

Kristinekr,
I have had the same problem you speak of not on my kitchen cabinets, but on doors that I painted, around the knobs. It seems the paint kind of "melts" from the body oils. This same thing happens with finishes on stained cabinets, it's just not as noticeable.

Ah. Yes, softening could be happening from the top down.

You'll still need to clean as I described, though, before you repaint.

A too-harsh cleaning product could be softening the finish there. What do you use?

If it is softening from skin oils, that's not good enough paint. A tough poly topcoat then WOULD help. But poly will darken or add a yellow/amber cast to the paint color, unless you use water-based which may not perform any better than the paint.

"Melting" is a good description of what is happening to the paint.

I use various cleaning products--just whatever I have in a spray bottle that is an all purpose cleaner--sometimes method, sometimes windex all purpose. I have used a magic eraser in the past, but that seems to dull the finish.

When I am doing a good cleaning, I spray all the cabinets down, wait a few minutes that wipe them down. I have to scrub a bit in areas that have food spilled on them.

What is a rec cleaner for painted cabinets?

We are going to get new cabinets in a few years and I want white again--but the type you see at the store that are already white--that type of finish shouldn't chip or melt--right?!!