Under the United States Constitution, you have a constitutional right to gee married, if you so desire. Accordingly, under New York Law, a probation officer cannot prevent you from getting married.
However, there is another issue related to the terms of the probation agreement. Specifically, a probationer may be prohibited from associating with other people on probation. Therefore, it is possible that you could be violated for associating with your finance or spouse. Even in this case, however, you would be violated for associating with another person on probation; as opposed to than marrying another person on probation