Does 反面 require contrasting clauses?

Question

I encountered the following example sentence in a book describing the uses of 反面:

仕事を辞めて自由な時間が増えた反面、緊張感もなくなってしまった。

Since I quit my job, I do have more free time but I also lost my nervous feeling. (I'm aware this might be too figurative)

That translation sounds unusual to me because I do not think "not having a nervous feeling" and "having more free time" contrast each other enough to be joined with "but". I think they should be joined with "and". However, all the sources I found state that 反面 is used to present different sides.

My questions are:

1. Does the Japanese sentence, by virtue of using 反面 (and probably しまった), imply that the speaker believes "緊張感もない" is a negative consequence?

2. Is 緊張感 considered a positive emotion in Japan?

3. Would the sentence make sense if the clauses were combined with だけでなく or just the て形?

EDIT: My reasoning behind question 3 is that, based on the translations of 緊張感 (Jisho.com reference), "仕事を辞めて自由な時間が増えただけでなく、緊張感もなくなってしまった" would mean "...not only do I have more free time, I also lost my feelings of nervousness." Is this not a natural way of using だけでなく?

Answer 1

1. Does the Japanese sentence, by virtue of using 反面 (and probably しまった), imply that the speaker believes "緊張感もない" is a negative consequence?

Yes.

2. Is 緊張感 considered a positive emotion in Japan?

Not always. It depends on the context.
緊張 usually has a negative connotation, but 緊張感 is often used in a positive meaning. And here in your context, it is used as a positive emotion.

3. Would the sentence make sense if the clauses were combined with だけでなく or just the て形?

「仕事を辞めて自由な時間が増えただけでなく、緊張感もなくなってしまった」 doesn't really make sense. 「仕事を辞めて自由な時間が増えて、緊張感もなくなってしまった」 doesn't sound too good, either. I would rephrase it as:

仕事を辞めて自由な時間が増えた｛が/けれど/けれども｝、（逆に/反対に）緊張感はなくなってしまった。(も→は)
仕事を辞めて自由な時間が増えた｛が/けれど/けれども｝、（同時に）緊張感もなくなってしまった。

Answer 2

1. Yes.
   反面 is used to contrast two things. In the sentence, "自由な時間が増えた" is mentioned as a positive consequence of quitting the job so "緊張感もなくなった" is the opposite. しまった here adds the nuance of "regrettably."

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2. As Chocolateさん said, it depends on the context and 緊張感 is often used in a positive meaning. 緊張感がない usually means "not be careful," or "being careless."

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3. No. The two clauses are contrary, so you cannot combine them with だけでなく or て-form.

Answer 3

Try, reading 「緊張感もない」 as "nothing to keep me on my toes."

It definitely does not mean "nervousness" here. "Energy" would work better, similar to the way understanding Japanese use of 「テンション」 works better if you think in terms of the German word, and not the English.

緊張 is a tension between opposing forces, like the tension on a spring or piano wire.

(afterthought)

Checking the meanings of 緊：

https://dictionary.goo.ne.jp/jn/58754/meaning/m0u/

https://en.wiktionary.org/wiki/%E7%B7%8A

I like the explanations in Japanese better than the ones in English, because they seem more clear to me. (You can switch to Japanese on both of those.)

「[引き締める]{ひきしめる}」、 for example.

and of 張:

https://en.wiktionary.org/wiki/%E5%BC%B5

https://dictionary.goo.ne.jp/srch/en/%E5%BC%B5/m0u/

「張る」 comes quickly to mind, anyway -- ca. 「[気を張る]{きをはる}」。

It's very clear that 「緊張」 maps well to tension.

In physics, tension can be a very useful thing.

The first time I heard a teacher I was working with say, 「今日はちょっとテンションアップしましょう。」 in a classroom, I did a double-take, because she was clearly not using it in an ironic sense. She was asking them to focus on classwork.

Even so, when she said on a different day, 「おマエら、ちょっとテンションダウンすぎるよ！」 I did a second double-take, for two reasons. One, if they were American kids, the atmosphere would have been just about perfect for a really good session of unplanned exploration.

(I'm always happy to use side-tours to reinforce principles I'm working on.)

But she wanted them significantly more focused that day. We had a good lesson.

This was a good teacher. She was strict, but she also knew how and when to loosen the reigns. I could not do the things she did in class, at least not until many years later, and I still go at it a different way.

Tension means something to the Japanese that it doesn't mean to most Americans, and probably most people from the UK, Canada, Australia, and New Zealand.

(end-afterthought)