Can't marry against parents will but don't want to hurt them

Hi this is Rohit. I hve a relationship frm past 4.5 yrs, now the situation is we are happy with each other. My gf she tried her best to convince her family members then her parents too, bt her family members were ready for us but suhey denly they turned back and evn they told her parents tht do allow her to get married with a maratha guy. She has tried her best to convince her prents but they are nt ready to accept it and they wnt her to get mnarried in their caste tht is brahmin, now the situation is she cant hurt her parents too as she is the eldest one in her family and she dnt hve brother too, she is afraid if she does love marriage then no one will tlk to her parents and they wil also nt talk to her as well, so pls plssssssss give me a solution whre we can convince them easily so they wil agree for our love marriage...