Thank you to all who provided feedback to my previous post (Grammarly and "couple"); I was pleasantly surprised by so many taking the time to respond. I received constructive arguments and explanations from many, the upshot of which is that Grammarly is correct, although a COUPLE OF respondents pointed out that the construction lacking the preposition is now colloquially accepted, so I might be justified in skipping the preposition in a character's speech.
To summarize a COUPLE OF responses, "couple" is a noun in the usage and the following noun (whether raisins or girls) should be part of a prepositional phrase describing "couple." The phrase is no different from others like "horn of plenty" or "hall of fame;" that is, neither "horn plenty" nor "hall fame" makes any sense.