The love I have for my husband and the love I have for my boyfriend feel very different.
My husband has been there for me through so much and has never wavered in his love and support. He stood by my side through homelessness, through mental health crises. He's the person who knows me inside and out. He can read every subtle movement and knows exactly what I'm thinking. He holds my deepest secrets and is the best father I've ever met. He speaks my love language of Acts of Service. He's the keeper of a decade of inside jokes. We can have whole conversations just out of facial expressions on the opposite sides of a crowded room.
Nobody else could ever have that.
As far as if he asked me to stop seeing other people--that's a tricky one. If I wasn't actively seeing anyone else and he wanted it to stay that way, I'd oblige.
But I personally think it would be unfair to ask me to cut off people that I love and care about because of jealousy. If he needs more attention or time or affection, I'd rather him tell me that. In polyamory, it's more important to address the root of the jealousy than to avoid it.
That said, if he asked me to break up with my partners, I'd say no. He would have to decide if that was something he could live with, or if he wanted to leave the marriage. I wouldn't leave him.