Hans writes to someone who used to be close and now isn't, at least not in the way they once were. The speaker wants to be there during this person's hard times, and says so plainly: if you ever hit your lowest point, tell me, and I'll be there. The line "we didn't own each other" suggests there was never a formal claim between them, which may be why the speaker feels unsure of their place now.
The mood is quiet and a little aching. The speaker has gone silent, but not out of coldness. They believe they aren't needed, so they hold back. The last lines turn the poem toward the speaker's own need: they wish they could lean on this person too. The repeated "i wish i can" sounds almost like a whisper, as if the offer of care is also a hidden request to be wanted back.