third time is the charm(third time lucky (or US third time is the charm): used to express the hope that, after twice failing to accomplish something, one may succeed in the third attempt. NODE Alexander Demidov)
throuple(Three partners in a romantic or sexual relationship; ménage à trois: The throuple walked into the restaurant on Valentines Day. UDwiktionary.orgAlexander Demidov)
Trinity Lavra of St. Sergius(The Trinity Lavra of St. Sergius is the most important Russian monastery and the spiritual centre of the Russian Orthodox Church. The monastery is situated in the town of Sergiyev Posad, about 70 km to the north-east from Moscow by the road leading to Yaroslavl, and currently is home to over 300 monks.wiki Alexander Demidov)