I have to go, so just a quick prototype, for one-way (only grow) - it just happens to give the result you want for the example, but I know if there was a 2-face separation on the ear loop, you would expect the separated part to disappear, and this doesn't do it:

And this goes the other way:

So if you do the first, then the 2nd, you're probably fine, but there's also a question of how many iterations (I did 100) - you need to implement a "while" loop. It can be done, I think I'll start another question for that and link here, but that tomorrow…

I have to go, so just a quick prototype, for one-way (only grow) - it just happens to give the result you want for the example, but I know if there was a 2-face separation on the ear loop, you would expect the separated part to disappear, and this doesn't do it:

And this goes the other way:

So if you do the first, then the 2nd, you're probably fine, but there's also a question of how many iterations (I did 100) - you need to implement a "while" loop. It can be done, and I've wrote an example on how to do it here:

Implement "while" loop in Geometry Nodes

And here's the screenshots from my answer there:

Mat Fix:

Loop Test:

Loop Body:

You can unmute the node above, so that the selection both grows and shrinks. This will yield such result:

(look at the ear)