To answer the question you will have to know when you moved (June) and when the losses occurred. If the partnership went bankrupt before you moved you will allocate all the losses to the first state. If it went bankrupt after you will have to prorate it.
The 7/12 fraction you used might not be correct if it went bankrupt before the end of the year. Most of the losses could be in the first state.
I found some guidance in the help pages for Turbo tax regarding [part year situations]:
Method 2 for allocating earned income seems most appropriate:
Method 2: Estimate the number of weeks or months you worked at that job while you were a resident of one state and divide it by the total of weeks or months you worked at that job to come up with a factor. Then multiply the factor by the entire income from that job. Examples:
If you worked at that job the entire year and moved in early May, you earned roughly 4 months' worth of income (1/3 or 33% of your total income) in your old state. Multiply the income from that job by .33 to obtain the allocation for your old state; the remainder is allocated to your new state.
If you worked at that job for 39 weeks total (4 weeks while living in your old state) you'll divide 4 by 39 to come up with a factor of .1026. Then multiply the income from that job by .1026 and allocate that amount to your old state; the rest gets allocated to your new state.