leaving at altar (verb) jilt: abandon, betray
Sinonime: abstract, absurd, chimerical, idealistic, illogical, impossible, impracticable, improbable, inapplicable, inefficacious, infeasible, inoperable, ivory-tower, no go, nonfunctional, nonviable, otherworldly, quixotic, romantic, speculative, starry-eyed, theoretical, unattainable, unbusinesslike, unfeasible, unreal, unserviceable, unusable, unwise, unworkable, useless, visionary, wild, won't fly
Antonime: practical,
sensible