The person who has shared with me both the happy and the sad times and especially who stood by me in difficult times.
Someone who shared with me the small happiness in our everyday lives.
ご質問ありがとうございます。
"The person who has shared with me both the happy and the sad times"＝「楽しい時、そして悲しい時を私と共にした人」
"and especially who stood by me in difficult times."＝「そして得に困難の時に私の側にいてくれた人。」
"Someone who shared with me the small happiness in our everyday lives."＝「私たちの日常生活の些細な幸せを共有した人。」
ご参考になると良いです！
アメリカ合衆国 
