On The 4Th of July, I posted a question about a boy I like, and now I have a new question.?

Ok so one off my best friends has a cousin named Devin. He knows I like him alot and she knows I like him alot, and she's ok with it. Recently, I was on the phone with her and she was at her grandma's house and he lives right next door. He had his girlfriend Kayla over, and he came next door for a second and took the phone and told me he was takin so hop off. But then my friend said he only said that because his girlfriend was their, and that I look way better than her. I still really like him and that kinda hurt my feelings because I know when know one is around he's a completely different person. He's told me the only reason he won't go with me is because I look young. So how can I make myself appear older, and what should I do????? Please help guys!! and please don't give me any bullshit about how I shouldn't give him the time of day cause he's an . I know this, but I'm helplessly so lovin him so please just help me!!!!