bf has cuckold kink but I only want him

He really gets aroused by the thought of me being with other guys. The thing is, I want to see him aroused too, so I would tell him that I’m a little into it and that I’m open to the idea in the future. He often brings up the idea of gangbang... how two guys would suck on my tits, another one fucking me, and one more in my mouth. I like the thought of how pleasurable it might be, but the truth is, I only want him.