I don't get what ''元気よくとはいかない'' means


''~とりあえず、新学期。まぁさ、元気よくとはいかないけど、でもこんな天気もいいし、桜も咲いてるし、もう少しだけ愛想が良くてもいいんじゃないかしら？''

What はいかない is? is it like てはいけない (must not/don't have to)? If so, why はいけない
and not はいかない?

Could you break '''元気よくとはいかない'' down?

Thanks in advance!




いかない is the negative-form of 行く, and いけない is the negative-potential-form of
行く. Both have a number of special usages when written in hiragana.

Here, ～とはいかない means "won't go like ～", and it's a way to say something won't
go/proceed/happen as expected. This と is a quotative-like-と, and this は is a
topic/contrast marker. とはいかない and てはいけない are different:

  * 元気よくとはいかないけど  
(literally) although it may not go like "Cheerfully!"  
→ if not cheerfully in particular

  * 元気よくてはいけないけど  
although you must not to be cheerful

Examples:

  * すぐにとはいかないよ。  
Not right now, you know.

  * これで完成とはいきません。  
(Unfortunately) This doesn't make it complete yet.




いかない is the negative-form of 行く, and いけない is the negative-potential-form of
行く. Both have a number of special usages when written in hiragana.

Here, ～とはいかない means "won't go like ～", and it's a way to say something won't
go/proceed/happen as expected. This と is a quotative-like-と, and this は is a
topic/contrast marker. とはいかない and てはいけない are different:

  * 元気よくとはいかないけど  
(literally) although it may not go like "Cheerfully!"  
→ if not cheerfully in particular

  * 元気よくてはいけないけど  
although you must not to be cheerful

Examples:

  * すぐにとはいかないよ。  
Not right now, you know.

  * これで完成とはいきません。  
(Unfortunately) This doesn't make it complete yet.

