Okay, so she likes you!? So what? What's in liking? Liking is not loving! And you're already so excited dreaming of getting into his/her married life!
So first find out if he/she loves you. And see, you can guess at it, you can approximate it, but in the end if you want the correct answer, you have to ask! So go to him/her and ask "Do you love me?... Would you ruin your married life for me?". Either he/she will hit you with a frying pan and stuff dirty socks into your mouth or he/she will hold you tightly. If you're hit with a frying pan, you should go to a hospital and also promise yourself that you won't go eying married men/women again. And if you're held tightly, uh…I hope you know what to do then .
   Now, if he/she loves you then you guys should sit down and talk to his/her husband/wife. If he/she is sensible enough, he/she will sign in the divorce papers and let her/him free. If not, buy a helmet!!
Good luck!