How to talk to my mom about going away with my boyfriend?

So before I get a bunch of angry moms freaking out, I am 19 years old. I've been with my boyfriend for years. We both just finished first year of university and we were long distance so I didn't get to see him very much (he's in Ireland I'm in Ontario.) so anyways we always talked about going to Barbados this summer cause his family has a beach house there and my mom absolutely refuses. It wouldn't be just us, a few of our friends would go as well and I just find it extremely unfair that they're all allowed to go but I'm not. I'm super open with my mom, she knows we've been having sex and I have a job so I have enough money for my flights etc I'm not asking her to fund it and I know I TECHNICALLY don't need her permission cause I'm an adult and for most of the year I don't even live at home but I don't want to ruin my relationship with her all for this vacation. What could i say or do to try and raise my chances?