How long does honeymoon phase last?

Just wondering how long does the honeymoon phase or the excitement and newness of a relationship last before it just gets old or in a routine or boring? I know relationships have different phases..

it sucks cause the newness don’t last forever when you are just learning them and it’s new and fresh! I mean what are the phases of a relationship? Never had a long term relationship that lead to marriage if that happens, just curious. If only one could stay in the beginning of a relationship 😉