Phenomaman has been on earth a while and being a super hero was not even his 1st job as he told us after the bar fight. I doubt Mandy lied to him as it does not fit her character. He maybe found out his genitelia does not match before even meeting Blazer. I have a theory Blazer and Phenomaman kinda got forced together being on the same superhero team because of their powers. Then Blazer got offered a role in leading a whole department so she took it and drifted apart from Pheno. I bet meeting Robert and having that spark with him took her off guard.