I posted it either here or back at FoH, but I had a girlfriend once that had to remain in contact with her ex because he had promised to keep paying off some debt he racked up in her name. Every month it was a fiasco and crying-fest when she'd try to get the money from him. I was not going to pay for it (ended up with enough debt from her anyway, but that's a different story). I told her it was up to her, she could remain in contact and eventually get the money each month, but be a mess, or cut all ties and just deal with it herself. She used to always go meet him for the money on her own, but asked if that bothered me. I told her no, I trusted her, why would it? I was showing my trust in her by letting her go, I said. Then one day she comes back and tells me that he had tried to kiss her so she just left. Again she asked me if I was mad. I said sure I was mad at him, but why would I be mad at her? She told me she left immediately afterwards, and they were in a McDonald's so it wasn't like he was going to rape her right there, so other than knowing he's a douchebag and either bringing me along next time or never meeting with him again, of course I wasn't mad.
Well, months later when we got in a different fight, she brought that back up and informed me that she had *wanted* me to be jealous, and tell her not to go, or insist that I come along (before the kissing incident), and that it bothered her that I was so nonchalant about her seeing her ex-boyfriend. I countered with asking if there was any reason I should be jealous, was she fucking him, did she lead him on, did she give him any reason to think he could kiss her? She said no to all of them, but she still wanted me to be jealous. Apparently flat out telling her that I was letting her go because I trusted her wasn't good enough, I was supposed to live up to some storybook romance where I got terribly jealous and confined her to her quarters or something.
I'm still not sure, and for all I know she lead him on/fucked him, who knows? Needless to say, she was fucking nuts, but the point is that you never fucking know exactly what someone wants. She might be telling you that she's talking to her ex so that you can be jealous. Of course, if that's the case there are further problems on the horizon, but you never really can tell. She might also be doing it because she believes in honesty, which is a good thing.