I was similar when I was still dating - I preferred one person at a time (the only benefit - if one is really looking for a long term commitment, at least - I can see of dating multiple people is it’s helpful to work out what you really want faster than if you see one person at a time).
It is ok at this stage to be exclusive, even if you’re still using the time you’re together to get to know each other better, rather than making big plans for the future.