The article studies the impact that the end of the two-party system since 2015 has had on the relationship of trust between the Spanish Congress of Deputies and the Government, marked by the diffi-culties in reaching the investiture with the consequent prolongation of the Government in office, on the one hand, and on the other, the first successful vote of no confidence. It analyzes the unprecedented circumstances of the different legislatures: failed investitures, repetition of elections, coalition government, testimonial no confi-dence motions without possibility of success, adoption of a constructive vote of no confidence without a result of political stability.The conclusion is that the intensive and novel application of the Constitution and parliamentary law in recent years in Spain does not seem to have led to political agreement, but to confrontation and parliamen-tary deadlock.