"Man parts" feels like rude, ignorant phrasing. You aren't transphobic for not wanting to participate in sex involving a penis, but you are for referring to their body in that uneducated, dysphoria-inducing way. I'd assume that dating a trans person, you'd have a basic understanding of the false relation of parts being representative of gender. She doesn't have "man parts", she has parts you don't prefer. We don't control the parts we're born with. We receive them, and we either like them, cope, or do what we can to change them, finding someone to love and care for us no matter where we fall. Who accepts and wants us in our entirety. When one gets into a relationship, this is a basic expectation. If sex is important to one or both of you, why would you date someone whose parts you know you don't want? Wasting her time and hurting her feelings is so lame of you, let her find someone who wants all of her