How does a prospective groom tell his fiancée about the two upcoming surgeries and their impact on saving money for the marriage, and how does he keep her?

A suitor is not obligated to inform his fiancée of his illness or surgical operations unless these are defects that necessitate annulment, and his ruling is that of a stranger to her until the marriage contract is concluded. If you promised to pay the dowry and complete the marriage at a specific time, and it became clear to you that you are unable to fulfill this except after a period, then you must inform them of that. If they accept, then all is well; if they refuse and annul the engagement, there is no blame upon them.