Breech of Contract - Separation Agreement

If a separation agreement states that the net balance of the home sale will be divided equally between husband and wife whether proceeds or losses.

In the event the home is underwater does this mean that both husband and wife would need to come to closing with 1/2 of the closing shortfall?

If either husband or wife can not or will not do that is that considered a breech of contract?

Thanks in advance for your response.

If the agreement does not specifically say that each party shall be responsible for the shortfall, then it is not implied. If the house is underwater, you may have to enter into a modification of the agreement to cover what the parties can afford.