This is the 8278th most frequent Japanese word.
弄
"弄" means "to play with," "tamper with," or "toy with."
The word '弄る' here indicates physically handling an object to adjust or repair it.
彼は古い時計を弄って直した。
He fiddled with the old clock and repaired it.
In this sentence, '弄ぶ' means treating someone's feelings lightly or irresponsibly, akin to 'toy with'.
人の心を弄ぶのは良くない。
Playing with someone's emotions is not good.
Here, '弄ぶ' denotes a gentle and playful action, often metaphorical to describe movement or interaction.