reconcile, become intimate
昵 centers on closeness and reconciliation: moving from distance or conflict to intimacy and harmony.
昵 combines 日 (sun, day) with 尼, which likely contributes the sound. The exact historical development is uncertain, but the character is associated with closeness and intimacy.
The sun 日 beside 尼 suggests warmth and closeness, like two people reconciling under the sun and becoming intimate.
For ジツ, imagine two friends reconciling and becoming intimate while eating jitsy (a made-up word for a cozy, intimate meal): jitsy -> ジツ.