I do a lot of Discover Scuba classes, and in each every diver has the opportunity to receive all appropriate instruction and get to the point of being able to "play in the pool." However, there are some who have more difficulty than others. With those I will stay late if they want. Equiopment issues like a leaky mask should not be a problem if the dive center has quality training and rental gear. Let your wife know that, and , when she does start her classes, be sure she buys a properly fitted mask before the first pool session.
DivemasterDennis
DivemasterDennis