Getting rejected *sucks*. But there *are* guys, both cis and trans, who are cool with getting involved with trans people, both MtF and FtM. That I know for a fact. What I'm less sure of is what specific advice to give your gf. My community of friends is very queer-friendly, and very open with each other about our lives, so these sorts of connections come together more naturally. All the advice that comes from my personal life, therefore, would be along the lines of "have a large, diverse group of friends, be open with them, and express interest freely to those that interest you." Buuuut, that might not be at all relevant for your lives.
I'm sure there must be message boards and support groups specifically for trans women that would address this issue specifically?
Best of luck!
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.