Best duo comps

I am a top main and my gf a mid main (mainly and always brand and she declines to think that any other champion is better only because big flames is better than dark magic or starlight or whatever else). We are currently d3. What would be a good champion to protect and help her better? I usually go Garen tank but for some reason (skill or meta) i can't just do the job properly in recent matches (50 or so). What do you guys recommend? Try to change her mind for the millionth time or change my main champ? Wich champ duo top/mid do best rn?