Last night, while talking with my girlfriend, I came across a construction that had me boggled: if I want to refer to a secular event in the past that could have, but didn't, occur, am I always bound to use the modal perfect structure? I.e. if, say, I penned an extended story about a kidnapping, would it be possible for me to say:
They held me captive for days and days. I could escape, but the Stockholm Syndrome kicked in, leaving me unable to take any action.
Or should I always say the following in such situations?
They held me captive for days and days. I could have escaped but (...)
Another set of examples:
We had enough funds. We could buy/could have bought this property, although at the time it was just a whim.
Is the "could have" form limited to relating to personal experiences, or is it perfectly fine to use it under more literary conditions? Which one is more preferable in the above sentences?