As you both will be on the lease, both will have to qualify for it. The landlord and property manager will take into account both your credit histories and your income. It the same as it would be if you were buying a home. You can use your combined incomes to buy a home for an FHA loan and a conventional loan. The only time that doesn't work is with a VA loan unless both of you are veterans and both want to use your entitlements.
If you'd like to discuss it in more detail, give me a call at 210-491-0021 x140. I have been helped clients buy, rent or sell since 1985. Here's a link to my website for more details http://MySanAntonioHome.net.