Alive99, oh I agree that whatever is going on in her head is not an excuse to treat someone poorly / give mixed messages. I've been on his end as well. Yes its very hurtful. The word "ethics" comes to mind. You're going to want to treat the people you are dating well, regardless of if you're serious about them, not, or confused somewhere in the middle. OP needs a direct coversation with her. In his post I could really sense that he likes her and that is really a hard thing to let go of. He may have to. Hopefully he will respond here though that's not always the case with new posters so we will see.

She may be at an age where she "should" be considering his feelings. Should is often a word I'm wary of though.

"sure, it is possible that this woman likes to fantasise too much and has er, lax/fuzzy boundaries with guys, and not think of consequences and is all over the place"

What do you mean by "fantasize too much"? What do you mean by "lax/ fuzzy boundaries with guys"? There is an air of judgment to your tone.