How does The Portrait of a Lady and one other text represent the concept “Only Connect: Perspectives on Self and Other."
Consider how each text reflects the values of its context and also how the theme of connection is represented thematically and technically.
You have asked a big question, and I am only going to be able to give a few suggestions for you to think about rather than giving you a complete answer. Firstly, however, for the other novel, the famous phrase "only connect" is actually taken from E. M. Forster in writing about his novel, Howards End, and so you might want to think about using that as your other novel to compare and contrast with The Portrait of a Lady.
The major theme of Howards End is connection and how we connect with others and within ourselves. As the novel shows it is actually incredibly difficult to connect with others, and even harder at times to sustain those connections. By examining two opposing families, the Schlegels (represeting imagination and idealism) and the Wilcoxes (representing commercialism, practicality and pragmatism) we are presented with two alternative ways of approaching forming connections. For the Schlegels, as is shown by their friendship with Leonard Bast, the personal relationship is infinitely more important than the public relationship, and they support the individual vs. the institution. Obviously, for the Wilcoxes, the opposite is true as social niceties and formalities and business ethics are the most important guide in our relationships.
Clearly the marriage of Margaret Schlegel and Henry Wilcox repersents, on her part at least, an understanding of the Wilcox mentality. What challenges their connection is Henry's inability to associate Helen's pregnancy and sexual transgression with his own affair with Mrs. Bast. However, at the end, he is able to reassess his own past actions, and the connection is maintained as Henry lives with his wife and Helen and her illegitimate child in Howards End.
As far as The Portrait of a Lady goes, clearly we see Isabel Archer's idealism and naivety preventing her from forming connections. It is her desire to experience life and to live it fully that cause her to turn down a marriage proposal from Lord Warburton. It is her mistaken belief that Gilbert Osmond will help her to achieve her dreams that cause her to marry him. Yet she is a character who internally at least never seems to be able to connect with reality and with the true nature of things. She always seems to allow her idealism to keep others at a distance. However, it is when tragedy strikes, and she receives news of the imminent death of her cousin, Ralph Touchett, that she is able to connect between her feelings and emotions and others. She defies her husband, even though this is going to bring her problems on her return, and goes to England to see Ralph die. Arguably, her final meeting with her beloved cousin and his urgings for her to be happy and then her confrontation with Caspar Goodwood and her subsequent refusal of his offer allows her once again to connect between her inner and outer life. Her decision to return to her husband, although hotly debated by critics, could be seen as her final decision to live the life that she promised to lead, fulfilling her responsibilities to both Pansy and Gilbert, rather than constantly dreaming after another life.