Hello everybody,
last night I watched my favorite TV show with English subtitles on, and though I've never payed much attention to such things while watching anything in English I would like to ask you to clarify this for me:
I have been taught to use the present perfect simple tense with "ever" and "never" but here are some quotes from the show that made me think twice last night:

"now I find out you're something I never even knew existed"

 "I can make you stay longer than you ever thought you could"

"I think she's my favorite girl you ever dated"

 "I never felt this way about any girl before"

as you can see they're all in the past simple tense. I'm sure there is nothing wrong with the subtitles as I can hear them talking that way.
Are there any exceptions to the rule of using the past perfect simple with "ever" and "never" or maybe there are differences between American English and British English about this?

Thanks for taking your time to help me.
In many sentences that might formally require the present perfect, the simple past is fine in conversational English. For example:

"I never felt this way about any girl before" -- fine in conversation, but I wouldn't use this style in formal English

"I have never felt this way about any girl before" -- acceptable in both conversational and more formal English

(I'm a British English speaker and, as you suggest, there may be usage differences here between British and American English.)

If you are referring to a period set entirely in the past, the simple past has to be used. For example:

"The ancient Greeks never established an empire."

Here you would not say "have never established".

Probably there are other considerations too. These are just the first couple of things that came to mind.
Thank you very much.