R. Kelly -- 'The Notebook' Inspired Me ... to Divorce My Wife

11:43 PM PT -- Kellys' ex-wife Andrea tells TMZ ... she doesn't believe "The Notebook" truly caused their split ... telling TMZ, "[The movie] came out in 2004 and we saw it together. Our divorce wasn’t finalized until 2009 so it’s impossible that the movie could have been the reason for our relationship ending. "

She adds, "We had been separated for 6 years at that point! The movie definitely did not end our relationship!”

R. Kelly is blaming Ryan Gosling for ruining his marriage ... sorta ... and it's all because of R.G.'s performance in "The Notebook."

Kelly just revealed some incredibly personal secrets in his new memoir, "Soulacoaster" ... including an explanation about why he decided to divorce his former back up dancer Andrea Kelly back in 2009.

Long story short ... Kelly claims after watching the movie, he realized his own 12-year marriage couldn't stand up to the romance featured in the flick.

Here's the explanation in Kelly's own words:

"As the film credits started to roll, I couldn't move. I burst into tears. People walking past me patted me on the back, trying to console me. 'The Notebook' was beautiful, and I was crying because its hero and heroine had died together.

But I was also crying because I remembered a Valentine's Day -- when a helicopter dropped a rainfall of roses -- that had come and gone ... My marriage had died. And there was nothing I could do to bring it back."