That seems a little counter-intuitive. I would understand wanting to treat them exactly the same if they were in competition for your affections and you wanted to not show favoritism, but if you've already committed to the both of them it would seem more prudent to treat them differently according to their own likes and dislikes. That isn't a show of favoring one over the other so much as valuing them individually for the unique quirks that made you romantically interested in them in the first place.

[The glory of being able to logic one's way through everything. If only he had been this good at it in school...]