HOW TO DIFFERTIATE BET A COUPLE?

I AM A BOY OF 23 YEARS OLD WITH A FAMILY OF 3 MY MOM DAD & SISTER MY SISTER WAS IN AFFAIR WITH A GUY FOR LAST 3 YEARS ANY ONE IN MY FAMILY IS NOT AWARE THAT GUY COMES TO OUR FAMILY SOME TIMES JUST IN CASE LIKE ON DIWALI FOR ANY OTHER OCCASION FOR GIVING A GIFT AND WE WERE THINKING THAT'S IT SHE IS WORKING IN REPUTED FIRM ON A VERY GOOD PROFILE FOR ATTRACTIVE SALARY & EARNING MORE THEN THAT GUY BUT (FIRST) HE EARNING LESS THEN HER. HE IS NOT OF OUR CAST. THEIR HOME IS ALSO NOT STABLE THEY LIVE ON ILLEGAL RURAL GOVERNMENT LAND. HE ALSO DON’T HAVE ANY FAMILY BASE, WE ARE BRAHMANS BUT THEY ARE MEAT SELLERS OF GOAT FISH PIG. EVEN THOUGH WHEN HE COME TO MY HOME FOR HAVING A WORD WITH MY FAMILY ABOUT THEIR MARRIAGE MY FATHER GOT A MINOR HEART ATTACK NO ONE IN OUR FAMILY IS INTERESTED IN GETTING THEM TOGETHER I NEED HELP PLEASE ANY ONE WANT TO ADVICE ME I WILL BE HIGHLY OBLIGED