If this is in fact real, and not some sort of joke or marketing stunt...

What seemed significant here was when she said, "I know everything is a joke with you..." My guess, without knowing these two, is that she likes the guy but he's immature. Or at least, less mature than she is. Or if maturity isn't it, she wonders whether or not he can be serious enough to make a lifelong commitment work. Something along these lines.

Her comment in the past that led to this idea was probably made with intent he took as funny, but which she thought had a modicum of truth in it. Like she was telling him in a coded way, "This is exactly how I do not want to be proposed to, and I know you're the type to try it."

Her reaction seems to indicate she takes marriage seriously, and wants a grown up for a husband, and is realizing just what a child he is -- whatever his other virtues may be. The fact that she didn't break up with him over this (not yet, anyway) suggests she does see a lot of worthwhile in him.

I don't think this has anything to do with money (as others are alleging).

She's not complaining about the ring. She's complaining about having a life commitment proposed to her over a shitty fast food sandwich. She's seeing her worries and suspicions about him confirmed, which is jarring and disappointing to her. She's not seeing it as cute.

I don't know what's right and wrong for other people, but his misreading of the situation suggests they have some things they need to work out. They need to be on the same page. Marriage is serious business. It's an odd institution in a very flighty age: a sort of old-school oath (even the term "proposal" misses the point.)

Best to err on the side of seriousness.

Now the irony, if anyone is still reading. I joke a lot too.

When I proposed, I did so in an uncharacteristically serious way. My wife, hearing me in a serious tone, thought it was weird, and blew it off. She didn't say yes or no. She said something like, "I have to pee."

Fortunately, it all worked out well, but she can only vaguely remember the moment. I had to do it a second time: "No seriously, I really want to get married."

Ideally this is a moment that happens exactly once in a life time, so you sort of have to get it right. And to get it right, the person proposing has to make it entirely about the other person: it has to be something tailored to them, which shows not merely earnestness, but an understanding of the person which indicates to them you're ready for this sort of commitment. That's where he seemed to screw up.

I wish them the best. But to everything there is a season, and except on TV sometimes, sometimes it's time to be serious.