a bit surprised I was to find this in OED2, evidently popularized a bit by Peg Bracken:

[Ger., lit. ‘shut door (or gate) panic’.]
A sense of alarm or anxiety (said to be experienced particularly in middle age) caused by the suspicion that life's opportunities are passing (or have passed) one by; spec. that manifested in an ageing woman who longs to (re)discover the (sexual) excitement of youth, and who fears being left ‘on the shelf’.

1963 P. Bracken I Hate to Housekeep Bk. ix. 92 The random housewife is often prone to Torschlusspanik, or fear of being locked in the park at night, after the gates are closed. 1977 Time 8 Aug. 21/3 She was haunted by Torschluss-panik (mid-life crisis). 1980 Times Lit. Suppl. 14 Mar. 287/2 She [sc. Mme de Staël] is perhaps history's most outstanding case of Torschlusspanik: the panic at the shutting of the door.