慕

Bottom heart radical ⺗ — the four-stroke form 心 takes when it sits beneath a character (compare with the 4-dot form). It indexes 慕 in the mental-emotional family alongside 想 think, 念 long for, 愁 worry. The heart on the bottom marks inward feeling rather than outward act — 慕 is the inward yearning of longing.

Top 莫 supplies the sound: mò drifting to mù with the regular vowel shift. Same phonetic powers 模 mold, 摸 touch, 膜 membrane, 墓 grave, 暮 dusk. 莫 itself depicts the sun (日) sinking into grass (艹...大) — the original graph for 'sunset.' Faintly semantic too: 慕 is the longing felt as evening falls, the dusk-pang of missing someone.