Hello and welcome to the forum!
I am hearing two things in your post. "Intensity" and "the amount of time spent with a new partner" and I'm not sure if they are the same issue.
What does "intensity" mean to you? Does it mean getting swept away in an emotional tornado of feelings and getting so obsessed with the new partner that you don't even desire your SO at all any more or at least for a while? And if it is for a while, then how long would it take for you to return to your SO with feelings of desire?
It sounds like your SO is setting some clear boundaries and you feel these to be restrictive.
I guess it would be good to become really clear about what you want. It sounds like you want to have the freedom to get involved with anyone at any time and to get caught up in the experience without having to worry about anything else.
If that is the case, do you think you would do better as a single poly person?
Or do you want to have a SO that is okay with you disappearing from time to time into intense relationships while they "hold down the fort" so to speak until you decide to come back?
Just throwing out some things to hopefully help you get really clear about what it is you want!
The key to life is in being fully engaged and peacefully detached simultaneously and authentically in each moment.