I agree. And the relationship cannot be THAT serious if she did not care to even mention it during 2 years. Ask her questions. If it seems fitting the situation, tell her what you told us. No shame in it.

You say you go to the gym. Do you do really intense cardio workouts there, stuff that gets you close to your max heart rate? HIITs? If you do not, try them, as they clear the head better than slow exercise. Something about blood flow to the brain.