ふか深fukaまるmaru
1.
To gradually increase in depth or intensity, often relating to emotions, understanding, or relationships.
2.
To develop more profoundly, suggesting an enhancement or escalation of a state, quality, or condition over time.
3.
To progress toward a more intricate or complex level in various contexts, encompassing both abstract concepts and tangible phenomena.
Example:
夕闇が次第に深まっていった。