病(びょう)気(き) byoukiだった dattaので node、私(わたし) watashiは waパーティー paateiiに ni行(い)き()ま()せ()ん()で()し()た() ikimasendeshita。 Since I was sick, I didn't go to the party. Literal Sick was [because-ので] I [topic-は] party [to-に] did-not-go [polite-ませんでした]. だったので gives the reason in past tense. 行きませんでした is the polite negative past. A straightforward explanation in polite register. healthsocial events~ので (because)
病(びょう)気(き) byoukiだった dattaので node、私(わたし) watashiは waパーティー paateiiに ni行(い)き()ま()せ()ん()で()し()た() ikimasendeshita。 Since I was sick, I didn't go to the party. Literal Sick was [because-ので] I [topic-は] party [to-に] did-not-go [polite-ませんでした]. だったので gives the reason in past tense. 行きませんでした is the polite negative past. A straightforward explanation in polite register. healthsocial events~ので (because)