rejoice, enjoy
怡 centers on a heartfelt sense of joy and contentment: rejoicing and enjoying something deeply.
怡 combines 忄 (heart) with 台, which likely contributes the sound and the idea of a raised platform, suggesting a lifted or joyful heart.
The heart radical 忄 beside 台 (a platform) suggests a heart lifted up on a platform of joy: rejoicing and enjoying.
For イ, imagine an eagle soaring high with a joyful heart: eagle -> イ, and the eagle's flight mirrors the lifted feeling of 怡.