is "dating for fun" the same as casual?

can you be "exclusive" and "dating someone for fun" (as opposed to, dating them with the intention of having children together and promising to stay together forever)?

I said I wanted to date for fun and he started talking about having sex with "no pressure"...
Then when I explained that I don't do "casual" for health reasons, he said actually he meant exclusive but anyway it's better that we just remain friends. Is there something that doesn't seem right about this explanation?

Yes you can be in an exclusive just for fun relationship. Been there done that, but it's sort of one of those terms that is predetermined. Sounds to me like the guy was just trying to go with whatever meaning you wanted to mean. I would be hesitant cause you're right, the situation just doesn't seem right.