Length hasn't been the problem at 6.5" but girth at 6.25" turned out to be the problem that we had been having for 31 years. We thought my wife had medical and/or psychological issues, but it turns out that I am just to girthy for her. She has been dilating her vagina for over a year and is finally making some progress. One morning nearly a year ago she came up to bed and asked if I would like to try butt plugging her, I didn't even know that she was dilating her ass, well to our surprise she can take me in her ass and I can even thrust vigorously after she has relaxed, of course we use plenty of lubrication.
The other morning was the first time that I could get half way into her vagina so she is progressing on that front, so to speak.