Not 'thinking' or 'feeling' something is unrealistic. What is realistic is not acting or repeating.
Its a lot like new parents, they are enamored by everything their baby does. But no one else wants to hear about every detail and no one else wants to talk exclusively about your new baby.
Likewise-your partner may not want to hear about your new partner daily and in fact may want to hear about your relationship together!
I mysekf have never experienced NRE in poly. However-it has nearly destroyed our family when my husband has experienced it.
Also-remind yourself that the base truth is-all of those good feelings are chemicals dumped into your brain- they will fade. Its NOT that this new person is perfect. Its just a chemical bath you are taking that feels great. The same way meth addicts start out.
For me personally-I have a rule for myself. I don't see new people more than once a week and preferably in a group dynamic for at least a year. Also-I limit conversations to no more than a handful of texts in any given week. Same duration of time.
Sexual contact of any kind-not until after AT LEAST a year or two of being a friend that socializes comfortably with my whole family/household.
It allows me to build friendships while holding all of that excitement at arms length-never letting the fire burn out of control. It also means my life loves have PLENTY of time to build their own friendships with my potentials and to grow comfortable with them before negotiating my romantic entanglements.
But, I dont know anyone else like me in that regard.
"Love As Thou Wilt"