Does having a boyfriend improve or reduce your productivity and concentration?

please don't give cheesy answers like 'if you can balance your time well...' etc. I'm interested in realistically, on the whole, do you think uni students (yes i am one) do better academically compared to their potential, with a boyfriend or without a boyfriend? and whichever way the pendulum swings, why? basically, one of my friends got a boyfriend lately and her grades first dipped but later rose, I wondered if it is more distracting having a boyfriend or not having a boyfriend and wanting one....