When I was in grad school in astronomy, one of my professors told me "many a promising young researcher has run their career aground on the rocky shores of tides."

The mathematics involved in the theory of tides are formidable. Even in homogeneous, tidally locked systems things can get complicated very quickly.

But tides are nevertheless very important. One two objects pass very close to each other, tidal effects are substantial and can actual destroy one of the objects: https://en.wikipedia.org/wiki/Tidal_disruption_event

There’s been some backpedaling lately in the astrophysics community about whether a tidally locked planet could still maintain an atmosphere and potentially support life. More modeling on how such at atmosphere might work has turned from “no” to “maybe”.

See also:

https://en.wikipedia.org/wiki/Roche_limit

https://en.wikipedia.org/wiki/Roche_lobe

Indeed given that we now think most of the heavy elements in the universe were created in type 1a mass-transfer supernovae, we can ultimately thank tidal phenomena for the existence of things like rocky planets and humans.

destruction (or nearly) via tidal mechanics happens in several of larry niven's short sf stories