Many questions can be posed about dating this psalm. This Psalm has no information about that. Reading Psalm 55:13–14 can make one think of a specific event (see the notes on those verses).
As emotions often play a role in the Psalms, we are regularly confronted with certain comments, shouts, or sighs. Just as in life, a Psalm is an expression of struggle, fear, thankfulness, and much more. This is a Psalm from the life of someone who struggles/is being oppressed.
The author is being oppressed and is fearful (Psalm 55:1–9)
The hostility and the misdeeds (Psalm 55:10–15)
The friend who became the enemy (Psalm 55:20–21)
Trust in God (Psalm 55:16–19, Psalm 55:22–23)
1 Au chef des chantres. Avec instruments à cordes. Cantique de David.