You decide to take on her form and become a babe yourself;
Although as a man you weren't displeased by your body, you never were sexually attracted to it. The thought of waking up every morning and seeing a hot babe in the mirror greatly turns you on.
With how frequent the shift has become in recent years women with the mind of a man have become fairly common, so has the opposite. In fact some dating sites have added options for such people. Women seem to particularly enjoy the company of women who have embraced their new found manhood.
As your new self finishes taking form; you learn everything about your partners life before merging with you and all the secrets to being a woman, her final gift to you as her will subsides to yours.