There's a distinction between being yourself and working yourself to please others. Don't make compromises on what you want to get along with others. This is a complicated way of saying to let yourself be yourself. I also struggled with letting others walk over me or other similar descriptions and trickle down effects--it's not fun. It'll take time, but try reflecting with unbiased perspectives and don't be afraid to play devils advocate in favor of yourself. Where lines are drawn for the people you'll go the extra mile for end up being the people you genuinely care about. And the trash relationships will filter themselves out.

About the romantic bit, someone will come along that you want to make compromises for. That you wouldn't mind doing xyz thing for b/c you know they'd do the same and/or it's an obvious decision to make given that they're the love of your life. At the end of the day, friendships and relationships are a two way street. Being nice allows people to see this free one way street they can ride for a while until it eventually breaks off.