to drop, to let go (as in "stop holding", work in a literal context of "holding a glass" as well as a metaphorical letting go of an ex.)
Opposite (closest): festhalten
A thorough look at the meaning of "los", its various useful prefix verbs and the noun "das Los", and what a raffle token has to do with fate and parking lots.
los, lose, das Los, los sein, loslassen, losgehen,
A thrilling look at the meanings of "Spannung" and the verb "spannen" and the answer to how to say ‘relaxed’ and ‘excited’ in German.
die Spannung, gespannt, spannend, die Anspannung, entspannen
lösen, die Lösung, auflösen, ablösen, verlieren,
The core idea of this root was:
letting go, slacken off, relenting
And we can still see this sense in the English offspring, like last, let, lenient, latter or late.
By the way, the words relax and and release, though they would fit in here, apparently come from a different root.