Anche se i termini da chiedere vanno divisi, da regolamento, qui secondo me serve una risposta organica su tutta la frase, quindi: "I suoi matrimoni sembravano susseguirsi l'uno all'altro in modo non dissimile dal ciclo infinito e sempre uguale delle maree..."

Letto nell'ottica del contrasto tra "Tidal" ( of or relating to tides : rising and falling at regular times - http://www.merriam-webster.com/dictionary/tidal ), riferito a cosa costante e continua, e il successivo "but this one was different".

Il contesto è questo: "His fifth marriage was disintegrating, and he should have known how to behave, how to take the long view, how to take the blame. Weren’t marriages, his marriages, tidal, with one rolling out just before another rolled in? But this one was different. He did not know how to behave, long views pained him, and for once there was no blame for him to assume, as he saw it. It was his wife who was hav­ing the affair, and having it flagrantly, punitively, certainly without remorse. He was discovering in himself, among an array of emo­tions, intense moments of shame and longing." - http://www.randomhouse.com/highschool/catalog/display.pperl?...

userei questo immagine simile...vedi la mia risposta a roll out/in

Weren't marriages, his marriages, tidal with one rolling out just before another rolled in?
I matrimoni, i suoi matrimoni, non erano poi come le onde del mare, l'uno infrangendosi appena prima che l'altro avanzava