Yes, our relationship with Iran is in a better place than it was before the Iran deal. I believe we also (or did before Trump took office) had more leverage with Iran than we did before the Iran deal. Does this mean our relationship is perfect? No. Does this mean Iran is now our best friend? Hardly. Does this mean Iran isn't going to continue to pursue what is in their self-interest? No.
Well, perhaps it is too much to say we should "never" go to war with Iran. We shouldn't go to war with Iran over them acquiring nuclear weapons though. And war with Iran should be our absolute last option. Indeed, war should always be the absolute last option.
Again, I am a realist. I accept the proposition that states are going to act in a manner that corresponds with their best interests. If Iran feels threatened and intimidated, their desire to obtain nuclear weapons is only going to grow. However, if Iran feels like they have a place at the table and that the West is willing to work with them without always beating the drums of war, I believe the West can have an influence on Iran. Does this mean Iran will never obtain nuclear weapons? No. However, proceeding on war footing with Iran isn't going to stop their nuclear weapons program and will most likely only hasten it.