I am a big believer in crate training for both dogs and cats.
I have high drive working dogs who do sport and they must be crated when in the van at training or traveling. When they are old enough, they get free reign of the house... I have an intact male and up until a month ago, an intact female so they obviously were crated when we were not around to ensure no matings occurred. My pups are always crated until they are reliable in the house without my constant supervision.
My cats, they are crate trained as well. This way when I travel they are completely comfortable traveling with me. They get crated in the van, in the house and when we visit my parents for periods of time so they think it's no big deal. The result - excellent traveler cats with no stress being in the crates. I also do this with cat sized travel crates so they are use to that as well.
But, I would never confine a cat for no reason.. that is just silly. If the cat was sick, then yes, to ensure I could keep it away from other pets, to monitor it's behaviour, feedings, water intake and bathroom habits (multiple cat house here).
I would explain to your boyfriend that dogs and cats do not share the same emotions as we do.. maybe he is just not educated when it comes to this? Maybe set up a meet-and-greet with a behaviorist in your area? Have the BF and yourself, ask them question and tell them your concerns.