二ふた股またをかける

expression, ichidan verb

cheat on a partner; two-time

Specifically refers to being romantically involved with two people at the same time without their knowledge.

• 彼かれは彼かの女じょに二ふた股またをかけていたことがバレて、振ふられた。

  He was found out for two-timing his girlfriend and got dumped.

expression, ichidan verb

play both sides; sit on the fence

Figurative extension: to try to keep good relations with two opposing parties, or to avoid committing to one side. Less common than the romantic sense.

• 彼かれは二ふたつの派は閥ばつに二ふた股またをかけて、どちらからも信しん用ようを失うしなった。

  He played both factions and lost the trust of both.