I'm in a similar situation, only I'm a woman! I'm the one with all the freaky pets, but thankful my boyfriend is tolerable (he even bought a nice patternless gecko as a gift for me once!). He's ok with the geckos, but like your girlfriend, he is terrified of my snake, Bandula. Bandula is a 14 foot long Burmese python. My bf always has the chance to leave if he wants because he knows that asking me to choose would mean I'd have to show him the door. Educate you gf, many people lose fear when they gain knowledge... good luck!