This is a common assumption but not necessarily true. If you are a cisgender female in a het relationship, one of the first things that comes to mind is that your het man is telling you that he is actually gay and has a sexual interest in men -- and was never really interested in you. This is harsh assumption.
While this may be true, it is not always the case. A man who is heterosexual, may be just that...his interest in a sexual partner is a woman, and interest in a partnered relationship is with a woman. Just because the het male desires to be female, and has sex reassignment surgery and transitions to a female persona with female genitalia, doesn't mean that once he transitions to female, that there has been a change in mind set for sexual preference or interest. However, with the new physicality, he now a she, YOU will find yourself with a partner that is now physically female.
Your relationship sexually will take on a different dimension being considered a #lesbian relationship not only by change in his>her physicality, but viewed as such by society. It will be important for YOU to determine your needs and desires in the relationship, and to communicate those to your partner. While your partner may not be gay, she is now Lesbian. If you stay, knowing you are not lesbian or bisexual in any other situation, it may simply mean that YOU are bi-capable.
For more information on what I feel it means to be "bicapable" see my post on this subject. #trans #bicapable #lesbian #heterosexual #sexuality #partners #change #adjustment #whatnext #socialstigma #socialview #perception #authenticself #M2F #F2M #dontmakeassumptions #relationship #cisgender #female #male