A problem of four sister...............

I have a friend who has three sisters. My friend is the eldest one. She is unmarried. Second sister, who is next to her, did love marriage. Her other two younger sisters hav boyfriends and they want to get married to their boys. My friend is still unmarried. her parents are trying for her marriage but it is not materialising. They are trying for arrange marriage. She is not getting idel match. She wants that her younger sisters should get maaried to their respective boys. but her sisters are saying they will get married after her marriage. now my friend is very upset. She sees no chances for her marriage in recent future and she is afraid that her sisters will loose their boyfriends if they did not get married to them early. can u help her by giving ur views.