You increase the capital account by the additional contributions and retained earnings and decrease the capital account by the distributions of return of capital and/or losses. Distributing gains doesn't change the capital account.
So in your case it would be:
1st year we lost money
Assuming you lost 20K, and the interests are even, it will look like this:
Bank Account 1 - Balance 80K // -20K loss
Partner 1 Capital Account Balance 40K // -10K - 50% of the loss
Partner 2 Capital Account Balance 40K // -10K - 50% of the loss
1st year we break even
Nothing changes - you break even, means the balance sheet doesn't change (in this example).
1st year we made money
Assume you gained 20K and kept it:
Bank Account 1 - Balance 120K // retained 20K
Partner 1 Capital Account Balance 60K // +10K, 50% of the retained earnings
Partner 2 Capital Account Balance 60K // +10K, 50% of the retained earnings
If you didn't retain the earnings, it would look the same as case 2 - no change.
Note that this is only the financial accounting, tax accounting might look differently. For example, in the US Partnerships (or LLCs taxed as) are pass-through entities, on in case 3 while you retained the earnings, the partners will still be taxed.
I'm of course neither CPA nor a licensed tax adviser. I suggest you get a consultation with one. Only a CPA can provide a reliable accounting advice or sign official financial statements, reviews and audits. Only a EA, CPA or an Attorney specializing in tax law can provide a tax advice.