Joking to a friend (girl) about getting married?

I was joking to a friend that i will be going back to my country to get married and she asked to who and said if im joking its not funny with a sad face. Ive been friends with her for about a year and i think she likes me a lot but she wont tell me i dont know for whatever reason. she has a boyfriend but hangs out with me more than the boyfriend and the boyfriend hates me a lot for that. anyways could she be getting sad that im leaving or that im getting married? we've been jokingly saying we will get married to each other. also what could be some reaons that a girl likes you but she wont tell you that she likes you. You might ask how do you know if she likes you? well here is a clear sign. i've told her i like girls with straight hair, she naturally doesnt have straight hair but ever since i've told her that she always straigtens her hair everytime before we hang out. and she always makes me play with it and smell it. ive seen her with her boyfriend walking sometime and her hair wasnt straight. I've told her i like her but now i regret telling her cuz i was thinking if i told her my feelings towards her she would also tell me how she feels about me but she hasnt. this girl is confusing me a lot. the signs that she likes me are so clear and obvisious that i frequently get asked by people if were dating. please help with your opinions. thanks