A phrase from the novel "War and Peace"

[Honore]

Dear Teacher,

Would you please explain the part written bold in the following sentence?

"...And as long as my sister Natasha was engaged to her brother it was of course out of the question for me to think of marrying her. And it must needs happen that I should meet her just when Natasha's engagement had been broken off..."

Thanks and regards,

Source:
http://www.friends-partners.org/oldf...ce_b12c05.html

[Soup]

needs, adv.
Of necessity; necessarily: We must needs go.

needs - definition of needs by the Free Online Dictionary, Thesaurus and Encyclopedia.

[Honore]

Thank you very much and regards.

[Soup]

You're most welcome.