So frustrated! Help😩

I've been at my job for 3 years. I'm a swim teacher for kids. I love my job and I'm good at it! I have people specifically ask for me to be their teacher and Ive never had and issues there. My boyfriend also works with me, he's been there for a little over a year and they just promoted him to a manager position. I'm really happy for him he totally deserves it. But they also promoted 3 other people who haven't even been there for 6 months. And I'm still stuck just teaching! They know I want to move up and do more and they just don't! I'm so frustrated!! They say it's because I have limited availability (I'm a full time student with 2 jobs) but I've said again and again that I would happily work my schedule around whatever they need! And nothing still!!

I've been considering applying to another place that is very similar to my current employer. It's pretty much our competitor, they have available manager positions as well as other things I would love to do!! But I hate leaving a business I know so well just to start over elsewhere😞

Any advice at all! Opinions, anything!