I can tell that you guys handle this ALL WRONG.
Here's the deal ...
if you are a couple, i vote same side ... either you want to be together, or you don't
if you are dating, you gotta mix it up, same side sometimes, opposite others, predictability is boring ... now, the fun part, when sitting next to her, PURPOSELY sit too close, and when you bump her, just tell her to quit hitting you*
*this works extremely well if you can hit her breast with your elbow ... "seriously, keep your damn topside off my elbows! wtf!" ... be extra obnoxious ... don't just reach across the table to get the salt and pepper, reach through her to get it ... then kindly ask her is she would like any before you serve yourself ... damn i'm good