My girlfriend told me she's nonmonogamous when we first met but we were monogamous until 11mo in when I suggested we tried opening things. I had always been curious about nonmonogamy and wanted to try it. Also my girlfriend had a crazy schedule at the time and I wasn't having my sexual needs met. We also got engaged around this same time. Well we both dated some people and I figured out I'm definitely monogamous and should've worked on getting my needs met by her instead of others. She acted like she was single again and was really poor with communication and broke my trust and hurt me. We ended up closing the relationship and called off the engagement too. This all happened a few months ago and since then I'm really unsure what the future will hold for us. I really want to marry her but I'm really not ok with the idea of her having other partners. She's terrible with time management and from the previous experience with poor communication I just see myself getting hurt a lot even if her intentions are good.