was missing, used to miss, was losing, used to lose, was getting lost
Cuando eran niños, te pedía que encontraras a Dev cuando se perdía.
When they were children, I used to ask you to find Dev when he got lost.
— Devdas (2002)
Cada vez que me perdía por completo, me tiraba en el agua helada.
Every time I got completely lost, I’d throw myself into the freezing water.
— Mommy (2014)
Adondequiera que iba, él se perdía.
Wherever he went, he got lost.
Mary pensó que Tom perdía su tiempo al estudiar latín.
Mary thought Tom was wasting his time studying Latin.