彼(かの)女(じょ) kanojoを o思(おも)う() omou激(はげ)し()い() hageshii気(き)持(も)ち() kimochiで de胸(むね) muneが ga一(いっ)杯(ぱい) ippaiだった datta。 My heart was full of intense feelings for her. Literal Her think intense feelings [with-で] chest [subject-が] full was. 彼女を思う激しい気持ちで is a relative clause: 'intense feelings of thinking about her.' 胸がいっぱいだった means 'heart was full.' loveemotionsrelative clause modifying a noun
彼(かの)女(じょ) kanojoを o思(おも)う() omou激(はげ)し()い() hageshii気(き)持(も)ち() kimochiで de胸(むね) muneが ga一(いっ)杯(ぱい) ippaiだった datta。 My heart was full of intense feelings for her. Literal Her think intense feelings [with-で] chest [subject-が] full was. 彼女を思う激しい気持ちで is a relative clause: 'intense feelings of thinking about her.' 胸がいっぱいだった means 'heart was full.' loveemotionsrelative clause modifying a noun