How does Romeo demonstrate the attribute of staying true to oneself other than in his love?

Your question is somewhat unclear, but try this. After Romeo and Juliet are married, Romeo tries to stop Tybalt from fighting; he thus is being true to the husband of Juliet that he is and the son of the Montague family which he also is. However, when Tybalt kills his friend Mercutio, he goes after Tybalt to avenge that death, also true to the "man" that he is expected to be in the society in which he lives. Without knowing exactly what your question is really asking, it is hard to be text specific, but all that is listed here is actually in Act III, Scene 1.

Thanks guys both are very critical answers