If it is from the sale of the main home, it may not be taxable. I can understand you getting a 1099-S for half the sale or not at all, for the whole amount is just wrong. You can ask for the issuer to correct it zero since your partner has the full amount on their 1099-S.
If they won't, you will need to see if it is taxable. If it was a main home, go through the sale section and enter your half of the 1099-S. If it was a rental house or a second home, it gets more complicated. I think the easy way out of this would be to indicate the sale on sch D and then subtract the amount under other income.
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