I keep thinking about the fact that I'm never gonna get married. he proposed in November and I…

I keep thinking about the fact that I'm never gonna get married. he proposed in November and I really don't think he meant it. but his brother proposed to my cousin and they are getting married two months after and they don't even have a baby. like what is so wrong with me? I know he'll never really wanna marry me. he says he will but idts