salamz dear mariam jaan!!
i think he is not worth it!!cause if he was like a real afghan muslim guy. then he shouldn't have dated u @ first place!! coz it is forbidden as u know in our religion n as well as in our culture!!
so, if he isn't agreeing to marry now then he has not much of ghayrat!!! to keep his words!! if he loves u ..... n considering u've converted to islam n struggle a lot to win his love!! but all he is doing is being a stubborn lill guy!!so dear sis, i suggest u forget about him!! n find someone else, another afghan guy who can understand and appreciate ur struggle in bringing urself closer to ALLAH(S) n to him!!