My girlfriend tends to be a completionist as well. She would often try to 100% a game she's playing, or at least to get as close to it as feasible.

But what surprises me the most about her approach is that she's completely chill about it. She doesn't force herself through miserable shit just to get an achievement.

And my experience with completionism is completely different. There's always an achievement that plain sucks. Getting 100% in Dark Souls 2 involved a lot of boring grinding and getting through the game 2 and a half times on the same character. Getting 100% in Lunacid forced me to grind a useless spell from bunnies for two hours.

I don't know, I just feel like it is better for me, my time and my mind to not see achievements at all, to not think about them and be focused on games themselves. The system is clearly not for me haha.