It differs from situation to situation... For me, I don't think I'll ever date or be in a romantic relationship again. We both viewed eachother as the other's soul mate, we still do, but life isn't always the most fair. It's a empty feeling, I don't think I'll ever not feel that way... However, I can function in my day to day life. Most days are good days, but there's always that little feeling that I know the days could be better if he was here.
It's taken me a LONG time to enter this mindset. If you asked me this a while ago, the tone of this answer would've been a lot more depressing and frustrating... Therapy has helped me heal the most.