ぼくたちの仲はもう終わりだ。

we

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

relation; relationship

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

now; soon; shortly; before long; presently; already; yet; by now; (not) anymore; further; more; again; another; the other; interjection used to strengthen expression of an emotion (often exasperation)

to finish; to end; to close

be; is; indicates past or completed action; indicates light imperative