While I more often hear men use the term "Friendzone", I've seen and heard of women doing something similar (getting angry/offended with a male friend that won't date her), so I'm directing it at both genders.

The purpose of having a friendship is to have a friend. A friend is someone who's company you like, and who you trust having around you. It's not rare for friends to have Feelings for each other sometimes - sometimes it's mutual and you end up dating, but more often it's one-sided and is just something those friends have to work with, usually by having a clear, mutually respectful conversation where everyone knows what to expect.

No one is "put" in a "friendzone" - you were already friends. You put yourself in the Friendzone when you befriended your friend. Presumably you liked being their friend, at some point, and they liked being your friend.

Since you already get to be around them and share your life with them as a friend, the ONLY thing you aren't getting from a Friendship is Sex.

Your friend isn't doing anything bad by not wanting to have sex and only wanting to stay your friend, they aren't "putting you" somewhere undesirable or hurting you. The fact that they want to stay your friend makes them a GOOD friend.

And if you abandon your friend because they don't want to have sex with you, you are a bad friend.

Some people might say "but I HAVE to abandon them, it hurts too much to NOT be able to have sex with them!" And... okay, I'm not dictating to you what your priorities should be. But to the Friend that YOU changed on, and decided you want to have sex with, you are a bad friend. Because you don't even LIKE having a friendship with them, and seem to think there's no other purpose to having a friendship with them if they "only" want to be friends.