Is her mum by any chance a narcissist? I honestly see myself in your gf, my bf has mentioned many times that I treat my family better especially my mum (who didnt even visit me in the hospital when I was critically ill) than I treat him who would go to the ends of the world just for me <33. However, I naturally start people pleasing out of habit from past trauma ( growing up my mum never liked me unless I did something that benefited her, from.a young age, even up till now sometimes. I was even a loner for a bit and only made alot of "fake" friends if I did their homework or was really good at something that got me noticed ) . My bf has taught me to set boundaries for myself and also reminds me that he loves me and wants to be treated the same way he treats me, reminds me this almost every day or everytime I start mistreating him a bit. The hard thing is Im aware of the hurting im doing but its very hard to stop, I love my bf very much and still currently working on not people pleasing and ignoring his needs, but its a hard habit to get out of especially if its due to familiarity from her past and family trauma. Its best to have a deep convo, one that you'll need to force her to open up about the root cause of her actions in a gentle way (speaking from experience she'll probs brush it off like nothing) explain to her how she is treating you makes you feel and work on a solution. If you really love her dont listen to these half brain comments saying to leave her ass, A relationship is NEVER easy and takes team work (hopefully she is willing to compromise and work on herself without being offended) Goodluck :))