"In Undertow" by Alvvays explores the complexities of relationships and the difficulties that arise from mistakes and misunderstandings. The song expresses a sense of resignation towards the inevitability of certain consequences and the impossibility of turning back time or undoing the past.

The first verse acknowledges the attempt to hold on to something, despite knowing that it is ultimately futile. The speaker also understands a mistake made by the other person, but it seems that this understanding is not enough to undo what has been done. The idea of astrology and the moon are brought up, perhaps as an example of something that many people believe in but that the speaker does not see as a solution to their problems.

The chorus emphasizes the idea that there is no going back after certain things are said or done, and there is no way to undo what has already happened. The repeated use of "no turning back" reinforces this idea of irreversible consequences.

The second verse suggests different ways to cope with the aftermath of a mistake or a difficult situation, such as meditating, playing solitaire, or taking up self-defense. The speaker again asks what is left for them and the other person, but this time suggests that there may not be a clear answer. Psychology and mood are dismissed as possible sources of guidance or resolution.

In the third verse, the speaker again acknowledges the attempt to hold on to something, but then asks what comes next. There is a sense of openness to suggestion, perhaps an indication that the speaker values communication and collaboration. However, the ending line "time to let go" suggests that ultimately, the best course of action may be to accept what has happened and move on.

The outro repeats the chorus with a sense of finality and disappointment. The phrase "so uninspired" suggests that the speaker may have hoped for better or different outcomes, but is resigned to the reality of the situation. Overall, "In Undertow" is a song about grappling with the aftermath of mistakes and the difficulties of moving forward.