The experience of seeing a play performed as compared to reading a novel is summed up by the idea that reading text is usually visualized in the reader's mind; but drama bring that vision to life in a live performance. Reading a novel is usually a solitary experience, so we as readers have our own singular interpretation.
A play's performance allows an audience member to see another person's interpretation of the text. The director interprets the playwright's words, but the actors also give their interpretations of characters. Sexuality may be contextualized in the lines of a play on the page, but sex can also be conveyed in a stage performance with body language, physical gestures and facial expressions.
An intimate play like The Glass Menagerie (which only has four characters) owes much of its dramatic potential to individual performances; and how each character portrays sexuality is a part of that. The main example of seduction that occurs is in Jim O'Connor's decision to compliment Laura, to tell her she's pretty, to ask her to dance, and to kiss her. We learn she has liked him since their school days, and so his behavior has a deep impact on her. But Jim is not romantically interested in Laura and is in fact engaged to another girl. He seems to think he is "bringing her out of her shell" but in his efforts to awaken her romantic feelings, he insures she will remain alone and sad.
The performance of this crucial scene relies to some extent on the underlying potential for sexual contact between these characters, the ultimate expression of physical romantic intimacy. But it seems clear this will never happen; and so one strong theme of the play is unsatisfied sexual tension.