So if Russia doesn't and will not ever accept nato troops or Nato in Ukraine, that only leaves the option of ending Ukraine. Since the war can't go on forever nor does Russia think they can just give up, because that would leave Nato closer to it's borders than it was before.

I not for a second believe that western leaders are so stupid and actually blinded by """principles""" that they don't understand this. They still just seek unconditional Russian capitulation (and regime change) or just keeping the war going as long as possible.