Final answer:
Based on the information provided, there is not enough context to accurately determine the content of Mary's letters to Gulliver. A close examination of the specific text in which these characters and letters are featured would be needed to provide a correct answer.
Step-by-step explanation:
The question appears to relate to the literary analysis of letters within a fictional context, perhaps referring to a narrative similar to Jonathan Swift's Gulliver's Travels or another work with characters named Tom, Mary, and Gulliver. However, based on the provided information, there is not enough context to ascertain the precise content or sentiment of Mary's letters to Gulliver.
The themes mentioned in the data provided speak to general contents of letters such as war events, comments on news, and business dealings, but they do not specifically address the relationship between Mary and Gulliver or the nature of her letters to him.
Given this, we cannot accurately determine whether Mary's letters are romantic, scientific, frustrating, or revealing of a plot without additional context from the specific text in question. A thorough reading of the text where these characters and letters are mentioned would be necessary to provide a correct answer to the student's question.