@SmilingCamel55,
Usually people who compromise too often and to their detriment have co-dependency issues,they are often "people pleasers" and are not in touch with their own wants and feelings.I am not saying that you are one of these people,just stating some facts that I have read about.If you want to stop over-compromising,you are supposed to get in touch with yourself,learn to set boundaries,learn to take care of you first and build a heathy relationship with yourself first,then you will attract healthy individuals,just like yourself!Not easy but doable for sure!Identify what is deal-breaker behaviour for you in a relationship and start one with people that match your criteria,don't expect them to change with time,often it's an illusion that we can change someone so if you start compromising at the start,you will continue doing it and feel miserable about it!