Does inter-cast marriage mean that you are tagged as an outsider in the family no matter how much you try to adjust?

I don't think so. My sister married someone out of our state and has gelled well with her in-laws. Part of it comes from her in-laws' temperament — they have embraced her with open arms. Part of it comes from her efforts in feeling part of the family. She doesn't think herself to be from another family or caste and treats her in-laws as her own family. I think the right attitude plays a big part here.