if a problem or a disagreement comes to a head, it becomes so bad that you have to start dealing with it.

Things hadn't been good between them for a while but it all came to a head last week when Phil failed to come home one night.

• the early bird catches the worm.
• the earth moved
• the ebb and flow
• the ebb and flow of
• the ebb and flow of something
• the end justifies the means.
• the end of the line
• the end of the road
• the eye of the storm
• the factory floor
• the facts of life
• the fag-end of
• the fag-end of something
• the fairer sex
• the fair sex
• the fat is in the fire
• the feathers fly
• the final curtain
• the final straw
• the fine print
• the [first/highest/next etc.] rung on the ladder
• the first rung on the ladder
• the first string
• the first thing
• the first thing in the morning