Anonymous3: To be fair, this is just common sense.
If Diana had sex with a normal man she: A) probably wouldn't even feel it being invulnerable and all, and B) The moment her pussy starts squeezing she'd rip that normal human's dick off.
If Clark had sex with a normal woman he: A) probably wouldn't even feel it being invulnerable and all, and B) The moment he felt good enough to lose even a tiny bit of control he would do a super thrust that would break the woman in two.
The only ones these two could ever have proper sex with is each other.
If Diana had sex with a normal man she: A) probably wouldn't even feel it being invulnerable and all, and B) The moment her pussy starts squeezing she'd rip that normal human's dick off.
If Clark had sex with a normal woman he: A) probably wouldn't even feel it being invulnerable and all, and B) The moment he felt good enough to lose even a tiny bit of control he would do a super thrust that would break the woman in two.
The only ones these two could ever have proper sex with is each other.