"wird schon gehen" = "I will handle my situation somehow"
This implies: I catched from a glimpse up to full extent the future consequences and activities due to the result of current decision.
When it is clear to me what will follow, I might not tell you because
- it might burden you (emotionally) which I don't want now.
- you might not understand it / takes unwillingly amount of time to explain it now
When it is unclear to me what will follow, I might not tell you because
- what comes into my mind as idea is to blurry
- I might fear the (near) future and I don't want to tell you (as the listener) these for various reasons: you might not understand them / they might burden you emotionally [like in the song]
- when I (as the speaker) have no clue what to do and I know I have/ will follow the duty/ task to keep it going (without you (as the listener))
These instant ideas about future can be neutral - just there is at least an idea/ foreshadow of it.
More usual is to think of a future that requires something to do from me I don't like to do. So somewhat negative with a wide range of negative and a wide range of doing.
The last three lines are talking about the topic / conclusion of first three lines:
- first three lines say "nice to see you - and each time you go - your departure gets emotional worse for me"
- thus last three lines talk about "to not see each other for a long time - I will manage it without telling you now what I fear it will be for me - and sometimes it makes me sad"