ok lovely and I like that. Its a lovely challenge to play that out :-).
Yes mid twenties is just fine, I am not too keen on too young characters. I was thinking about making her mid30s/end30s so at least 10+ years older than him. I can imagine her being a little frustrated in her job/life/relationship. I can see him bringing some fresh air into that. Her boyfriend's probably really focused on work - too focused.