on again

on again, off again

Irresolute; wavering in certainty or constancy; inconsistent. Commitment from the board regarding the merger of the two companies has been on again, off again since the plan was first proposed. Mike and I were pretty serious for about a year, but our relationship has been on again, off again ever since we graduated.
See also: again, off, on

on again

see under off and on.
See also: again, on
References in classic literature ?
The School-house are overruled--the fight is on again, but there is to be no throwing; and East, in high wrath, threatens to take his man away after next round (which he don't mean to do, by the way), when suddenly young Brooke comes through the small gate at the end of the chapel.