People tend to associate divorce with a pessimistic image.
Literal
Divorce [quotative-と] say [conditional-と] pessimistic image [object-を] tend-to-associate.
~と言うと…連想しがちである — 'when one says divorce, one tends to think of pessimistic images.' ~がちである (tends to / is prone to) is a formal suffix for habitual tendencies. 悲観的な (pessimistic) and 連想する (to associate) are formal vocabulary.