Breakdown of Он не мог не рискнуть ради неё, несмотря на свою трусость.
не
not
он
he / it (for a masculine noun) / it (for a neuter noun)
она
she / it (for a feminine noun)
мочь
to be able to
Questions & Answers about Он не мог не рискнуть ради неё, несмотря на свою трусость.
How does the double negative не мог не рискнуть work here to mean "couldn't help but"?
In Russian, combining не + a conjugated form of мочь (like мог) + не + an infinitive (рискнуть) creates a strong affirmation. It literally means "he could not not take a risk." This structure is exactly how you express that an action was inevitable or that someone "couldn't help but" do something.
Why is it ради неё instead of ради её?
The preposition ради (for the sake of) requires the genitive case. While the normal genitive for "she" is её, Russian adds an н- to the beginning of third-person pronouns (он, она, оно, они) when they immediately follow most prepositions. So, её becomes неё.
Why does the sentence use свою instead of его for "his" cowardice?
Свой is a reflexive possessive pronoun that always refers back to the subject of the clause. Since the subject "he" (он) is the one possessing the cowardice, you must use свою (matching the feminine accusative noun трусость). Using его here would strongly imply he took a risk despite another man's cowardice.
Why is written as one word for the first part, and what case does it take?