The difference between ‘stop to buy’ and ‘stop buying’

Let me make two sentences here to start my explanation of ‘stop to buy’ and ‘stop buying’.
1 I stopped to buy a can of Coke when I reached the convenience shop.
2 She has stopped buying things from the shop ever since she was cheated by the salesman there.

In the first sentence, ‘stopped to buy’ means I stopped whatever I was doing and bought something. I might be cycling, riding a motorcycle or driving. I just stopped cycling, let us say, and bought something from the shop.

As for the second sentence, ‘stopped buying’ here means has stopped going to the shop to buy anything at all since the incident of being cheated by the salesman at there.