Why would a girl go into a relationship if she wasn’t actually invested?

So it turned one sided pretty quick basically she made it seem as if she was above me saying usually people date people of their same attractiveness. Communication was non existent with her everytime I would try to talk with her she would say it’s triggering. Gift giving wasn’t equal I would go all out and buy her things of actual interests such as Ariana grande perfumes or a coach purse. She would get me cheap dollar store gifts or random things I would never use then she would just take it and use it herself. She would bully and make fun of me based on things about me being on the spectrum or having ocd even though she said it wasn’t an issue in the beginning. She would get upset and have temper tantrums when she couldn’t have her way and on certain occasions when she would get upset she would hit me. My big question is why why go into a relationship because no due to the scarring I no longer have the desire to have a good relationship I don’t envision having a family the way I used to it just seems like things people make up

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The problem with how this relationship is it played into my biggest insecurity and that’s not feeling accepted as someone on the spectrum
Why would a girl go into a relationship if she wasn’t actually invested?
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