You win

omg

An open relationship is when you can sleep with other people

Your definition is not what an open relationship means either. You realize married people can have open relationships too, right? Open relationship simply means that 2 people are in a relationship with each other, but they have sexual relationships with other people, usually as well as with each other. Sounds like the boyfriend doesn't really like OP anymore, and is just using the open relationship line as an excuse.

#3 That is not what an open relationship means at all. An open relationship means he wants to sleep with and/or date other people. Married people can be in an open relationship. Also I like to think OP is more likely to know what he meant than any of us since they were the ones who actually heard what he said.

Not all open relationships are open for both sides. One may simply have little to no sex drive but also lack jealousy completely. As long as both parties are in sync, it's all good.

So if married people can have a open relationship, why is my definition wrong?

But why is he a moron? Because he lost feelings for her? Not particularly his fault

The man is a noron because instead of simply moving on after losing romantic feelings for the OP, he is trying to persue a farce of a relationship for access to the cat.