Somehow I think it's cute how Karen is always worried about her age, because well... in isekai / old age stories their adulthood always start around the age of 15 which is a teenager for our standards.
That worry of hers is like she's insecure that just because she's 29 she's not fit to have a relationship with someone younger (Haru in this case) but let me be real here... if I was him, with a woman like that, I would never EVER cheat her, because man, she's a 10/10.