It's probably because her ex husband made her feel like she's old lol
Girl believe me once you hit 30s life is just different. 30s is a whole different animal. Majority have kids, own houses, have stable careers, and getting married. They're Koreans so I feel like that sense of "oldness" and urgency is translated in their characters too. Just an opinion tho. :)))
I just turned 30 and I couldn't agree more >< even tho everyone I meet can't believe I'm 30 and say I look in my early twenties, it still feels like I'm starting my downfall >< and I'm still single and struggling to find a good stable job, and society makes it so stressful to not be settled at this age, I'm in constant stress so I definitely understand the quarter life crisis
the way Haesoo talks about herself would make you think that’s she’s 65 without any context but she’s literally just 34 like girl you’re not even that old