My GF does that for me...can't tell you why though.
I am divorced and was SURE I would never fall in love again and just date and exchange when the mileage got high

...but then I met my GF. She isn't the most beautiful woman physically I have been with but when she looks me in the eyes I get all light headed...I seriously first thought I was over training, was dehydrated, calorie deficient you name it.
There is something there I can't explain that makes me not want others or have her leave me and though I can't give you a reason exactly why....I don't mind it one bit.
If you knew me personally even just 2yrs ago this is NOT where I planned to be.