fly in the ointment

US /flaɪ ɪn ðɪ ˈɔɪnt.mənt/
UK /flaɪ ɪn ðɪ ˈɔɪnt.mənt/
"fly in the ointment" picture
1.

vlieg in de zalf, smalle kantje

a minor irritation or flaw that spoils an otherwise pleasant situation

:
The trip was perfect, except for one fly in the ointment: the weather was terrible.
De reis was perfect, op één vlieg in de zalf na: het weer was verschrikkelijk.
His bad mood was the only fly in the ointment during the celebration.
Zijn slechte humeur was de enige vlieg in de zalf tijdens de viering.