Emotions, especially those formed through trauma, are powerful motivators and stimulators. Lots of people experience feelings of alienation from their body and their life. I've experienced that myself...it happened at an extremely stressful period of time.
Wanting to escape one's life, or one aspect of it is very common in human beings. We create fantasies, scenarios of different lives, different personas, different lifestyles. We nurture illusions that provide comfort and shield us from too much harsh reality.
I've listened to, and watched, many 'trans' stories and experiences. what they all have in common is a desire to escape some aspect of the self, and in particular to avoid the often heavy presuures of social or familial expectation...whether that be around behaviour, sexual orientation or conformity with gender roles. Some are escaping obvious traumas - such as rape or sexual abuse and a desire that this never happens again.
For some, usually men, there develops an urge to cross dress that usually starts in childhood or at adolescence ( Graysn Perry writes about this very well in his memoir) - and which has a strong erotic motivation. Most often these are heterosexual males but whose sexual orientation becomes directed towards experiencing oneself as female. This urge can completely take over their life, and relationships and marriages are negatively impacted. With the advent of queer theory and gender identity theory - an avenue and a justification for full time transition has now become available. People who once identified themselves as transvestites are now declaring trans identities.
However, one cannot really change sex. Sex is biological and not emotional. What distinguishes female people from male people is their biology and their body, not their personal preferences, imaginings or personality characteristics, nor their sexual orientation.
Women have dignity and integrity as adult human females - and they have, and deserve, privacy when it comes to certain types of situation in which their body or their bodily function is the most pressing matter.
People wth 'trans' identities are free to campaign for their own provisions.