Synonyms for Thwarting (same or very similar meaning)
WordNet sense 1 (preventing realization or attainment of a desire):
frustrating, frustrativeWordNet sense 2 (tending to prevent or hinder):
preventative, preventiveWordNet sense 3 (an act of hindering someone's plans or efforts):
frustration, foilingFrom the ODE community, based on WordNetadd/edit