My wife was honest about it all, that straightforward Midwestern kind of honest. We'd been dating and having sex for a while, maybe 6 months or so, and I'd expressed some surprise that she was still single six years after her divorce. I didn't know all the details of her dating life, except that she seemed to have 4 guys she liked to go out with and sometimes an overnight with. A couple of times when we had sex I was pretty sure I wasn't the first guy there and I made sure to tell her how good she felt. She took note. We were having this discussion in her bed in her home where we'd just had sex. "I have to tell you, I'm not a good candidate for marriage" she said, "I'm used to having different men in my life, and I know I'd want that again." It was easy to take the conversation from there. It took her a few weeks to internalize the idea she could marry me and I would want her to enjoy other men from time to time, but the idea grew on her and she brought it up again a week later.
