How do i get my girlfriend to be sexual continuously?

When my GF warms me up for sex or just for fun...and doing whatever she does to do so...it feels great, but there could be a situation where she stops for a break and doing stuff that doesn't have to do nothing with the arousal...like fetching a glass of water or scratching her tiny cute nose(sure, it's cute...but STILL!), and I don't know how to get her to stop those small breaks that get me want to skip sex that night...