Feeing betrayed

Not exactly, but I've definitely been in a dynamic where I gave much more than I received. When you're an inherently generous person, it's easy to give but others don't necessarily feel the need or want to meet you halfway or even partway sometimes. I'd say that expecting people to treat you exactly the way you treat them is a bit of a stretch. We are all different people after all. It doesn't mean that people can't find other ways to bridge that gap but it sounds like your friend didn't sadly. Nonetheless, some nuance to the spectrum of the human psyche definitely helps understanding why some people don't reciprocate exactly what we give them.