Monica's fine. She looks like a woman in her forties which is appropriate and she has a nice body especially if you like full figured gals. As to her personality, being 40ish her sex drive is naturally increased and she hasn't had a man in a long time and I expect that with the MC, who she hasn't since since he was a kid, turning out to be a good looking, very fit young man increases her libido further. When the MC gets there he finds out she's been drinking a bit because of the stress of her business and that lowers her inhibitions more even though she's a bit old fashion. So I don't think her behavior is that odd.