When a sitcom runs as long as Friends does, there are bound to be a few plot holes (although, Friends seems to have more than others), including one involving Chandler and Monica’s relationship. The beloved NBC comedy series created by David Crane and Marta Kauffman ran for ten seasons and 236 episodes, from 1994 to 2004. Although it has been off the air for over 20 years, Friends remains culturally relevant. People of all ages have watched the sitcom, ranging from those who tuned in when Friends was still airing to others who first discovered it on Netflix in 2015.

https://screenrant.com/friends-show-chandler-monica-i-love-you-plot-hole-explainer/