A little confused about 回不去的
I came across this phrase today 回不去的从前, at first I thought it meant cant go back to before/the past, but now I'm not so sure. I‘m sure in some sentences 回不去 is a verb, I think meaning cant go back to, right? However with this 回不去的 its an adjective right?
When I looked at it more I found the sentence 那是我们回不去的从前， I also found 回不去的 used with lots of other words, like 记忆， 爱。Would it be ok to translate 回不去的 as unrepeatable sometimes so you end up with sentences like 那是我们回不去的从前 That is our unrepeatable past or those are unrepeatable times.
I have used unrepeatable because if you have something like 回不去的记忆 if you said a memory you cant go back to, it sounds like something you cant think about again, or you cant recall maybe, but if something is unrepeatable it is often like saying you wont experience anything like it again. In which case maybe it almost like once in a lifetime lol
Can you explain just a little more about using this 回不去的 please. I also noticed you can say 回不来的, adding this 的 to this already strange structure is really confusing me I think lol.