love affair; romantic entanglement
Often implies a complicated or troublesome romantic involvement, sometimes with a hint of scandal or gossip.
He got involved in a love affair at work and quit.
That actor's romantic entanglement was in the weekly magazine.
恋愛 is a general, neutral term for romantic love or a love relationship, while 色恋沙汰 carries a stronger nuance of trouble, scandal, or messy involvement.
浮気 specifically refers to cheating or an extramarital affair, whereas 色恋沙汰 can cover any kind of romantic trouble, not necessarily infidelity.
Compound of 色 (いろ, 'color; love; sexual passion'), 恋 (こい, 'romantic love'), and 沙汰 (ざた, 'affair; matter; trouble'). The combination 色恋 reinforces the idea of romantic or sexual love, while 沙汰 adds a sense of complication or public fuss.