You should always tell someone if you’re trans or what your sexuality is. Knowingly violating someone's sexuality is disgusting by every standard imaginable.Let’s take it a step further: if a trans person does not disclose that information before entering a physical relationship, there should be legal consequences.Human sexuality is a very strange and complex thing. People can’t help what they’re attracted to, and by that logic, it shouldn’t bother you that someone wouldn’t be attracted to trans.
Even if the trans person isn’t the initiator, they have an obligation to disclose information that could negate the initiator's consent.
Yes, you absolutely do need to tell someone that you are trans before dating them.
Deceiving another person into sleeping with you is rape.
Knowingly violating someone else’s sexuality for your pleasure is wrong.
Yes, there’s a reason why water is wet, but it’s so basic that it’s somewhat difficult to explain.