It does not appear that you could marry her in Ohio: OH bars all marriage between first cousins and does not appear to have an exception for cousins by marriage only. See, for example, ORC Section 3101.01.However, it appears that roughly 1/3 of the states in the country, including CA, NY, NJ, MD, VA, FL, GA, AL, and SC, allow cousing marriage. So if you and she are serious enough, you and she could relocate to a state allowing first cousing marriage.