Anonymous, it looks like you have the following options:
1. Ditch the dojo, maintain current relationship.
2. Ditch current partner, go out with dojo mate.
3. Ditch current partner AND dojo, swearing off all romantic relationships. Move into monastery/nunnery.
4. Go out with both interested parties behind their respective backs.
5. Go out with both people and make no secret about it to them.
6. Have current partner and dojo mate fight a duel to the death over you.
7. Go out with your sensei.
The last few options should be more exciting, if that's what you're looking for...
Best of luck, and let us know how it turns out.
(this is purely tongue-in-cheek...I blame the medication I'm on right now)