What are the conflicts in the story "A & P" by John Updike?

In John Updike's short story "A&P," there is an external conflict and an internal conflict. Sammy, the narrator of the story, is merely an observer to the external conflict. This conflict occurs when three girls dressed only in their bathing suits come into the grocery store. People in the store are visibly shocked and Lengel, the manager, confronts the girls. He tells them that they must have their shoulders covered and be dressed decently when they come into the store. This "isn't the beach," he tells them more than once. The girl Sammy calls Queenie is embarrassed and blushes in shame. She and her friend try to explain that they were just running a quick errand for their mother, but Lengel is not interested in their reasons. He is more interested in the policy of the store and the expectations of the other customers. 

The internal conflict takes place in Sammy's mind. He is affected by Queenie's embarrassment. He does not like the fact that the store manager embarrassed the girls. He wants to be their protector and hero, so he decides to quit right then and there. The problem is that his parents are friends with the store manager and will be very disappointed in him. Lengel tells Sammy he will regret this action for years, and Sammy agrees that it is true. He knows his family will be upset. He is probably burning bridges in the community and destroying opportunities for securing a good position in the future. However, in that moment, even though he knows these things, he chooses to stick up for the girls. In the quote below, Sammy is answering a question his manager has asked him, but his mind is elsewhere. 

I thought and said "No" but it wasn't about that I was thinking. I go through the punches, 4, 9, GROC, TOT—it's more complicated than you think, and after you do it often enough, more complicated than you think, and after you do it often enough, it begins to make a lttle song, that you hear words to, in my case "Hello (bing) there, you (gung) hap-py pee-pul (splat)"-the splat being the drawer flying out. I uncrease the bill, tenderly as you may imagine, it just having come from between the two smoothest scoops of vanilla I had ever known were there, and pass a half and a penny into her narrow pink palm, and nestle the herrings in a bag and twist its neck and hand it over, all the time thinking. The girls, and who'd blame them, are in a hurry to get out, so I say "I quit" to Lengel quick enough for them to hear, hoping they'll stop and watch me, their unsuspected hero.

The action does not achieve the effect Sammy hoped it would. The girls do not even seem to notice that he quit and certainly do not think of it as a heroic action taken in defense of them. The quote below reveals the internal conflict that continues in Sammy's mind" 

I fold the apron, "Sammy" stitched in red on the pocket, and put it on the counter, and drop the bow tie on top of it. The bow tie is theirs, if you've ever wondered. "You'll feel this for the rest of your life," Lengel says, and I know that's true, too, but remembering how he made that pretty girl blush makes me so scrunchy inside I punch the No Sale tab and the machine whirs "pee-pul" and the drawer splats out.