A 30 year old unmarried woman from a low socio economic status, family believes that a rich boy staying in her neighbourhood is in deep love with her. The boy clearly denies his love towards this lady. Still the lady insists that his denial is a secret affirmation of his love towards her. She makes desperate attempts to meet the boy despite resistance from her family. She also develops sadness at times when her effo to meet the boy does not materialize. She is able to maintain her daily routine but however, remains preoccupied with the thoughts of this boy. She is likely to be suffering from: