I'll be happy to provide the information you need, Carm20.
First off, I'd like to say that the accounts I'll mention in my answer are for the sake of showing the How-do-Is, as a QuickBooks expert. It is always best to consult an accountant about accounting transactions.
When your partner pays an expense for your business, you can record a journal entry affecting your expense and equity accounts (or partner's equity account).
When you reimburse your partner, you can record a check against your business account. Then, categorize it as equity, which means you will use the equity account in the CATEGORY section.
You can check the detailed steps in this article: Pay for business expenses with personal funds. Though it mentions "you" as the payor of the expenses, the principle is the same when recording expenses paid by partners.
Post again if you have additional questions. Have a good one!