For native English speakers only: Would a native English speaker talk like this?

It sounds reasonable for an American English conversation.

The grammar is fine (for American English). The dialog seems a little stilted.

Why do you think it's stilted?

Because it's too long and sounds so formal, like B is reading lines from a script.

If I were B, and mad at A, I'd say something like:

"You think you know everything. According to you, every woman I've known is either a sociopath or gold digger. "

Then, I'd end it with "I'm not going to discuss this with you any more."

Then I wouldn't.

B (being sarcastic): Sure, I'll take your word for it. You're a self-proclaimed authority in dating, aren't you? You made me realize that every woman I've ever met or fallen in love with was either a sociopath or a gold digger.


Hmmm... that's a hard question. Stilted is just a feeling, but I will try.

The most obvious thing is the use of the word "self-proclaimed" in a tag question. I would get rid of that. Maybe I would say "You are such an authority in dating, aren't you?" (many of us would add a vulgar adjective to emphasize "authority").

The last sentence also seems a bit formal in this context. Maybe I would say "To you every woman...".

While not horribly unnatural, I'm afraid I have to agree that it doesn't sound quite natural, nor does B's sarcasm sting enough.

Unless there is an aspect of one or both of the characters that would lead them to speak in this way, I would suggest the following

A: Obviously, she only loves you only for your money. If you sold your car and quit your job, she'd be gone in a minute.

B (being sarcastic): Well you're the authority in dating. I now realize that every woman I've ever met or fallen in love with was either a sociopath or a gold digger.

There's a problem here as well in that B has taken this one comment of A to respond to in terms of all of his girlfriends. As it is, there is a vague implication that A has given B such "advice" in the past, but it's not clear.

I think you need to somehow tie into the exchange (without overwriting) some reference to how this advice about the one girl can relate to B's entire experience with dating. The following are suggestions made without a whole lot of thought:

A: Obviously, she only loves you only for your money. If you sold your house and quit your job, she'd be gone in a minute.

B (being sarcastic): Well you're the authority on dating, and there's no reason why any decent woman would mind me quitting my job and selling everything I own. I now realize that every woman I've ever met or fallen in love with was either a sociopath or a gold digger.

or

A: Obviously, she only loves you only for your money. If you sold your car and quit your job, she'd be gone in a minute.

B: This is what you always tell me.

A: Because it's always true.

B (being sarcastic): Well you're the authority on dating. I now realize that every woman I've ever met or fallen in love with was either a sociopath or a gold digger.

I'm not thrilled with either suggestion but I hope they illustrates the point I'm trying to make.

Ultimately, you know you're characters and while it certainly worth asking advice from others, how they speak in your story needs to follow naturally from the personalities you've created. By comments are based on the very limited profile you've given us. I've assumed they are educated white men from at least a middle class background.