I'm a virgin and I've been with him for over a year, should I ask him to be checked?

Yes you should definitely ask him to get checked. If he slept with only one girl before you and she slept with 5 guys you are sleeping with all of them. STDS can be carried for many years without anyone noticing. You could have and never have an outbreak in your life but your partner could. Also sometimes a lot of boys can be carriers and never have symptoms. So just just asked him to get checked just to be safe. By they way I think its great that are still a virgin that is something very special.