Which one of them was in the wrong here? 

When I was younger, I thought every engagement ring was bought by a partner who was trying their best but ultimately didn’t know exactly what their partner wanted. I thought every guy was just winging it with a proposal, hoping that she wouldn’t say no to him and praying that she’d like the ring. Now that I’m older and wiser, I know that a lot of couples go ring shopping together, and if they don’t, they discuss in depth the kinds of rings, engagements, and weddings that they want in the future. Well, they at least do that if they’re smart. 

A poorly executed surprise is not great, especially for an engagement. A lot of people don’t even like surprise parties, or their partner springing last-minute «surprise» plans on them. If you’re one of those people, imagine how you’d feel if your partner got on their knees and asked you to marry them in the wrong place at the wrong time. If your partner proposes to you before you’re ready, you might say no, even though you would’ve said yes if they asked you a year from now. If they spend all of their savings on an engagement ring that you don’t even like, you have to question why you should marry them in the first place. After all, that’s not a very wise financial decision, even if you do like the ring! 

The girlfriend in this story broke up with her boyfriend over a botched engagement attempt, and honestly, I can’t even be mad at her for it. He chose an expensive gesture over asking her what she really wanted, and that’s much worse than buying a ring that she didn’t like. He did that too, but maybe she’d forgive it if he were a better partner overall.