At first I did adore a twinkling star, But now I worship a celestial sun.” What, gone without a word? Ay, so true love should do. It cannot speak, For truth hath better deeds than words to grace it.” (2.2.17-19)” I leave myself, my friends and all, for love. Thou, Julia, thou hast metamorphosed me, Made me neglect my studies, lose my time, War with good counsel, set the world at nought; Made wit with musing weak, heart sick with thought (1.1.11).”
Proteus declares that his love for Julia has transformed him. Ever since he fell in love with Julia, Proteus doesn’t study, he argues with his friends, and isn’t very witty. Understood this way, love does not change one for the better.