(I know I know I'm an idiot for getting feelings for someone that's not poly. Save me from the scolding I already punched myself in the face enough 😭)

I was dating this guy briefly but it was very intense, and he just messaged me to say he was not engaging with me recently because he met someone else. He said how he feels like meeting me unlocked something in him that was really positive and that allowed him to connect with this new girl. This freaking sucks because I know him being into someone else means he is done with me. I am glad I brought something out so positive in him that it made him more open to connecting with others but, I now feel so discarded. Like he took what he needed from me and now is moving on ( I know this is just how it feels, but not necessarily what is happening, he is a kind person, I'm just in pain right now). What I find really hard about all of these is that it feels like no one thinks I'm allowed to be upset about this because I already have a partner. But I'm sure if I was monogamous and I told my friends this story they would all empathize with me a lot more, and I think the guy would've probably been more empathethic towards me also. It's like if you have relationship you are not allowed to be heart broken over someone else.