verb

talk or write persistently and tediously on (a particular topic).

I don’t want to harp on about the past

keep on about,persist in talking about,keep talking about,labour the point about,dwell on,expatiate on,elaborate on,expound on,make an issue of,discuss something at length,complain repeatedly about,nag someone about,badger someone about,hassle someone about,witter on about,rabbit on about