6" is a bit bigger than average, but not so much as to make any different, and in any case it's girth rather than length which turns women on. Women generally take the whole package when it comes to sex: and this includes romance, the right mood, treating her well, good oral sex skills, more romance and being romantic.
Even though a good lover is a good lover, extra size adds something that you cannot compensate for. A good lover who is also, say, 7" long x 6" girth is not only going to satisfy a woman, he's probably going to leave a mark on her that she'll never forget. But that is still no reason to work at being a good lover, and making every sexual encounter you have in your life a special one for both of you.