If she continues to live with a man she doesn't love for his money, the day will come when she will be utterly frustrated and between the devil and the deep blue sea.
In daredevil car races, there are moments when the drivers place themselves between the devil and the deep blue sea, trying to take the lead.
If we pay the rent to the landlady, we won't have any money for food; we are between the devil and the deep blue sea.