Hi,
There are a few methods but one you can try is "The Rescue"... you leave your bird in a room that is not that familiar like the bathroom (with the toilet lid shut of course). When you leave her there she will panic and start calling for you to come and "save" her. You let your boyfriend (or anyone else she hates) go in and save her.

When he gets there he can offer her treats and do the "ladder" a few times (step ups from hand to hand). This way she will see that he isn't really that bad and that he saved her from the scary ground!

Good Luck!