~dzurai ～づらい, ～辛い

In Japanese, ~dzurai ～づらい, also written ~dzurai ～辛い, pronounced the same way as zurai ずらい, and inputted in an IME as durai, is an auxiliary adjective that means a verb is "hard for you to do" because doing it causes you trouble or distress.

Manga: Komi-san wa, Comyushou desu. 古見さんは、コミュ症です。 (Chapter 5, 喋りたいんです。)

Usage

Like other auxiliary adjectives, ~dzurai ～づらい is attached to the masu stem of verbs, also called their "connective form," ren'youkei 連用形.

suru
する
To do.
shimasu
します
To do. (polite form.)
shi
し
Doing.
shi-dzurai
しづらい
Doing is hard.
Hard to do.
sh-dzuraiし辛い
(same meaning.)

Conjugation

The auxiliary ~dzurai ～づらい can be conjugated just like any i-adjective.

~dzurai
～づらい
Hard [to do.]
~dzurakatta
～づらかった
Was hard [to do.]
~dzurakunai
～づらくない
Not hard [to do.]
~dzurakunakatta
～づらくなかった
Was not hard [to do.]

Tsurai 辛い

The word tsurai 辛い is not an auxiliary adjective, it's normal i-adjective that means something is painful, tough, harsh, distressing, etc.

kodoku wa tsurai
孤独は辛い
Solitude is painful.
Solitude is tough.
Solitude is harsh.
Solitude is distressing.

Clearly, the auxiliary ~dzurai づらい comes from this tsurai 辛い.

The reason ~dzurai starts with dzu づ while tsurai starts with tsu つ is because suffixes sometimes undergo a process called rendaku 連濁, in which the first syllable gets a diacritic.

Zurai ずらい

In this post, づらい is being romanized as dzurai. That's because dzu づ is tsu つ with a diacritic, so, for me, it makes sense.

Note, however, that this dzu づ is actually pronounced exact same way as zu ず. In fact, you'll see that a lot of people romanize shidzurai しづらい as shizurai しづらい instead. They're the same Japanese word, it's just a different romaji for the same word.

Furthermore, in a computer, you'd type du to input a dzu づ, as typing dzu may get you d-zu ｄず.

Lastly, because dzu づ and zu ず are pronounced the same way, some Japanese natives may misspell ~dzurai ～づらい as -zurai ～ずらい. Make no mistake: although it sounds the same, the correct orthography is ~dzurai ～づらい, as it comes from the word tsurai つらい. ^{[「づらい」と「ずらい」正しいのは？ - writing-office.com, 2019-01-10]}

～づらい vs. ～にくい

The difference between ~dzurai ～づらい and ~nikui ～にくい, another auxiliary adjective that also means something is hard to do, is that ~nikui means something is merely difficult to achieve, while ~dzurai means that something is distressful to do.

In many cases, ~dzurai and ~nikui are interchangeable. That's because something that gives you trouble doing must also be difficult to achieve, and something difficult to achieve must also give you trouble.

wakari-nikui
分かりにくい
Understanding is hard to achieve.
It's difficult to understand this.
wakari-dzurai
分かりづらい
Understanding is distressful.
I'm having trouble understanding this.

yomi-nikui
読みにくい
Reading is hard to achieve.
It's hard to read this.
yomi-dzurai
読みづらい
Reading is distressful.
This handwriting is so bad it's making my eyes hurt.

ii-nikui
言いにくい
Saying is hard to achieve.
It's difficult to say something like this.
ii-dzurai
言いづらい
Saying is distressful.
Saying this would result in a level of drama I really don't wanna handle.

Note, however, that ~dzurai is more subjective compared to ~nikui. That is, something ~nikui is something that's generally difficult for anyone to do, objectively difficult. While something that's ~dzurai is difficult for you to do, because it implies it causes you distress, not anyone else.

wakari-nikui
分かりにくい
This is hard to understand because it's a complex subject and you'd need to be a genius to figure this thing out.
wakari-dzurai
分かりづらい
This is hard to understand because I'm a baka and all this information makes my head hurts.

A lot of times, saying, asking about, talking to, and other social actions get ~dzurai because it can be stressful for you to interact with certain people or talk about certain things with them.

Manga: Komi-san wa, Comyushou desu. 古見さんは、コミュ症です。 (Chapter 5, 喋りたいんです。)

Context: Tadano 只野 thinks about the school's most popular girl.
Komi-san wa
gakkou no madonna demo
hanashi-kake-dzurai bijin
demo nakatta.
古見さんは学校のマドンナでも話しかけづらい美人でもなかった。
Komi-san was neither the school's madonna
nor a beautiful person [who's] hard to [approach].
- hanashi-kakeru
  話しかける
  To approach and talk with. To start talking to. To begin a conversation with.
- Very literally: to pour a conversation onto someone.
In this panel, Tadano says he thought Komi-san was unapproachable because she was a "beautiful person." In other words, it's ~dzurai because she's way out of his league. This is a subjective matter. Someone at the same league as her wouldn't face the same difficulties.

Since ~dzurai has a subjective nuance, you'd use ~nikui instead of ~dzurai whenever you have an action that you aren't actually involved in doing.

For example, say you have an embarrassing memory of your childhood that you really want to forget, but:

wasure-nikui
忘れにくい
[It's] hard to forget.
Forgetting is hard to achieve.

You wouldn't say wasure-dzurai 忘れづらい here because forgetting isn't something you actively try to "do," it simply happens. It's "hard" for it happen, but it's not like you close your eyes and focus and put some tremendous effort and sweat starts dripping from your brow and hmmhmmmrrrmmmmrrrr!!!! *poof* Memory gone. That's not how it works.

Likewise, say you are talking about a pen and the permanence of its ink:

kie-nikui
消えにくい
Hard to disappear.

You wouldn't use kie-dzurai 消えづらい in this case because you aren't involved in this "disappear" verb. The ink is disappearing, not you.

On the other side, sometimes you have a verb where ~dzurai is more appropriate than ~nikui. For example: say you're in a social gathering you really don't wanna be, but if you just left, you'd hear a lot of trouble later. So it's:

nige-dzurai
逃げづらい
Hard to escape.

In this case, you wouldn't use nige-nikui 逃げにくい because, to begin with, the word "to escape" here is very subjective. It has to do with your personal situation. A lot of people could just leave that gathering and face no trouble at all. It's not objective enough like it's a maze anyone would find difficult to escape from. So you use nige-dzurai here, not nige-nikui.

The difference between ~dzurai and ~nikui is also said to be psychological vs. physical. ^{[「しづらい」と「しにくい」の使い分け - writing-office.com, 2019-01-10]}

Which is kind of confusing since something physically painful is tsurai.

What it means, though, is like the difference between something you think is impossible, and something that's actually physically impossible according to the laws of physics. That is, subjective versus objective. For example:

hanashi-dzurai
話しづらい
Hard to talk with.
Because that guy doesn't seem friendly. I don't like him. I don't want to talk with him.
hanashi-nikui
話しにくい
Hard to talk with.
There's a lot of noise in the background. Plus he's wearing a mask over his mouth. We are experiencing technical difficulties in our communication.
hairi-dzurai
入りづらい
Hard to enter.
Because someone I don't want to meet is in there.
hairi-nikui
入りにくい
Hard to enter.
Because this door is way too small. I would need to shrink to be able to go through here.

Again, don't let the "psychological" word mislead you. A lot of actions done psychologically aren't -dzurai because they don't distress you. For example:

kangae-nikui
考えにくい
Hard to think.

The verb "to think," kangaeru 考える, generally gets ~nikui instead of ~dzurai because it refers to something is hard to think, hard to conceive, unimaginable. Coming up with that thing is a task hard to achieve. If you used kangae-dzurai instead, it would mean that you are having trouble thinking, which is often not the case.