All of these sound a little dramatic, but being unable to say good bye is something that's pretty common to say.
A lot of times when people feel they are unable to do something, they say that they don't know how to.
これらはどれも少しドラマチックな言い方ですが、さよならが言えないという言い方は一般的です。
"I don't know how to"（どうやって～していいか分からない）は、何かができないと感じるときによく使われます。
I'm sorry I didn't have chance to say goodbye to you.
I wish I could have said goodbye to you before you left.
I'm sorry I couldn't say goodbye to you.
回答１訳：「さようならが言えなくてごめんね」
I'm sorry I didn't have chance to say goodbye to you.
回答２訳：「さようならを言う機会がなくてごめんね」
I wish I could have said goodbye to you before you left.
回答３訳：「帰る前にバイバイって言えればよかった」
日本語訳をそのまま訳すのであれば、回答１が一番近い表現になります。
「さようならを言う」は"say goodbye to you"でシンプルにそのままですね。
回答２のように「機会がなかった」という言い方もできるかもしれない。
細かいシチュエーションがあるわけではないので、「ごめんね」と謝る必要がどうしてもあった場合はもちろん謝るべきですが、仮にそういう場面ではなく、ただ単に「じゃあね」が言えなくて残念だった場合は、回答３のように謝る代わりに"I wish 〇〇"ということで「〜できればよかった」という表現の方が自然かと思います。
必要に応じて使ってみてください。
These two phrases mean the same thing, but "to see someone off" is a little less formal and it emphasizes saying goodbye in person. "To see someone off" means to see someone go / leave, which means to say goodbye to them in person / in real life.
example: I wanted to see you off, but I'm too busy to drop you off at the airport.
これら二つのフレーズは同じ意味ですが、"to see someone off"の方がインフォーマルです。これは直接別れを言うことを強調します。"to see someone off"は「～を見送る」という意味です。
例文
I wanted to see you off, but I'm too busy to drop you off at the airport.
（見送りたかったけど、忙しくて空港まで送ることができません）
1) Sorry I didn't get to say bye.
お別れの挨拶ができなくてごめんね。
もっと深刻な状況でしたら I'm sorry と言った方がいいですけど、この様なとき、多分相手も怒ってはいないと思うので、Sorry だけで大丈夫です。
2) I'm sorry. I didn't realize you'd left.
帰ったのに気付いてなかった。
ここの you'd は you had の略です。
you'd left の代わりに you'd gone home ともいえます。
The two sentences you see provided above are excellent ways to apologize to your friend for not being able to say goodbye. In the second sentence you will notice the term bid farewell. This means goodbye. This is a term that is used in our everyday conversation and would be appropriate for informal settings, like talking with close friends or family.
You can clarify that you didn't say good bye because you didn't have a moment to, you missed the opportunity, or for whatever other reason you were unable to at the moment. Apologizing for not being able to say good bye is polite-- there is a saying called the "Irish goodbye," which means where you leave a social event without saying goodbye. This saying can be considered politically incorrect however.
In an informal situation, there is no need to add 'I'm sorry' you can just use 'Sorry'.
The most common for Native speakers would be "Sorry I couldn't say goodbye".
インフォーマルな場面では、'I'm sorry'でなく'Sorry'だけで大丈夫です。
ネイティブスピーカーがよく使うのは、"Sorry I couldn't say goodbye"（さよならを言えなくてごめん）でしょう。
アメリカ合衆国 
日本 
アイルランド 
