If my girlfriend is a better writer than me, what’s wrong with her writing my papers if it’s my research?

I’m a college student with a girlfriend who occasionally helps me with papers. My roommate thinks it’s cheating, but here’s my take: She’s a better writer than I am, and helps me put my thoughts and research down in a coherent way. She doesn’t do any of the research – I do all that. Is it so wrong that she helps me make my research readable?

— Not a Cheater