Rule Out and Fly In The Ointment

Today's phrasal verb is Rule Out, which means
1-To exclude something or someone or make a decision not to consider something
 
The police have ruled out suicide and are treating it as a case of murder
Well, it's raining now.  That rules out our picnic today. 
He's ruling out going to medical school.  He simply doesn't have the money for it. 
The background check on him completely rules out our ever hiring him

2. prevent something or to make something impossible  

By moving his Bishop to A4 rules out my moving my Rook to E8

There are no avocados in the market today.  That rules out making guacamole.

Notes: Separable [optional] and transitive.

Today's idiom is Fly In The Ointment, which means
1-A small annoyance that spoils an otherwise pleasant experience or thing.

We enjoyed the play, but the fly in the ointment was not being able to find my hat afterward.
 I wish you hadn't decided to have anchovies put on the pizza. That's a fly in the ointment. 

 2-Someone or something that spoils a situation which could have been successful or pleasant.

Now that Martha has arrived at this party is a real fly in the ointment.  I was enjoying Robert's party until now. 

3-A drawback

It sounds like a good idea, but there must be a fly in the ointment somewhere.

I'd like to buy this car, but the fly in the ointment is that it doesn't come with air conditioning.