Marriage Delay and Family Conflict

We are 4 sisters. I am the third one. I have 2 elder sisters, one is 27 and other is 25. My parents are getting them married, they fear that my sisters might end up in wrong household. with fear of that, they are not marrying them. My second elder sister, who is 25, had a connection with a guy on phone and wanted to marry him. My parents said no, and they mentally tortured her, even its been some years and my father still doesn't talk to her, just because she offered her own proposal in front of my parents. Later, it was found out that my parents were right and that guy was not a good person. But now, after some years, she has another guy with whom she is talking, and today his mother came for my sister's hand, and my mother rejected. and my mother is saying that the guy is not good. In short, my parents don't want us to ever talk to a guy, and they are not even marrying my sisters as well. I don't know what my parents want. Its like the matter of pride for my parents. My sisters see and think that our parents doesn't think about them, as they are not doing anything to marry them. But my sisters has reached the age. Now everyone is thinking that the sister who came up with her own proposals twice is characterless. because they suspect, and have sometimes seen that she send him pictures, and is romantically involved with him. I also think my parents are somewhat responsible for this behaviour of hers, she is also stupid. I want to end this suffering, i don't know how to do that islamically. I don't want to do wrong to either my sister or my parents. I don't know how i can get my parents to marry them. I have tried talking to them multiple times, but they told me to stay away from this. How am i supposed to stay away even though i am also effected by that. The marriage standard of my mother is so high, that its nearly impossible to find such a guy and family to be honest. We are a middle class family, and my mother wants to marry us to an extremely upper class family, with servants, cars, businesses etc. She doesn't understand that upper class only marries in upper class. Instead she should see whether the family is islamic, etc etc. note: my parents had love marriage...kind off. their marriage is a disaster and torture or us and for them too. they think love marriage will only end up like theirs. Also, my mother hides the doings of my sister from my father, if he came to know everything, things would get real messy. I don't know what am i suppoosed to do in this situation?