I am about to shout out holy shit can you not to this lovey dovey couple elbowing me from behind in this quiet ihop.
When not all the books in the series are the same height.
When books change covers with editions so they don’t all match unless you buy the series in one go.
When some books are hardcover and some are softcover and it doesn’t match but you can’t find another copy.
When some covers are different in certain countries so you don’t get the main one which also happens to look better than all the other varieties.
Basically just books.
God damn them.