i'm single, and i do have a "semblance of a personal life". i go out once a week, play golf every now and then. there are residents that do a lot more than i do.
it's really up to you as to how much of your free time, and nights you want to devote toward "having a life". right now i am pretty focused on my training/career so quite often i stay in and read instead of going out, or stay a little later at the hospital to try and scavenge a case here and there. i choose to focus on my education heavily right now (currently a pgy-2), and by pgy-4 or 5, i'll revert back to my old ways and open up my social calendar more.
but there are the more "player" type residents too... they go out 2-3x a week, and really blow it up when they go out. those guys have iron constitutions. i don't.