while there is no legal obligation, don't you think there is a moral one?

Depends how far you are into the relationship.

Lies by omission are still lies.
Also, sounds like a good way to get a missing persons report filed.

Except the system we have now is much worse than a tiered system like combat sports have.

The biggest thing holding back women right now is the lack of sports science dedicated to improving their performance. Men had decades of a head start.

If you don't believe me that it makes a massive difference, women's marathon times massively improved as a result of improved research on improving their performance.

Cherry picked.
Try that with power lifting stats or most other sports.

Wouldn't that be like having HIV and having unprotected sex with your partner, because you are not obligated to say anything?

TIL being trans is a communicable disease

Being trans is not a communicable disease.
The emotional aspect of your partner finding out may perhaps be devastating since you cannot give birth.
Some relationships look towards a family unit and when I talk about the family unit i don't mean adoption.
I meant natural birth from your partner.

Perhaps as a Singaporean, South East Asian, we have a different kind of cultural view.
But that is just a my take.

See the above post.

I feel that relationships should have a certain degree of honesty.
Some men might find it ok, I think I am a little familiar with it , since Thailand have a fair amount of Transgender.
But even then, they will be a bit upfront with it.

Perhaps it might be a little difficult for someone to digest after being in a relationship with a "transgender" and she/he didn't mention to you about the situation.
If you are in love maybe it changes everything but still....