1
general::
Phrase(s): stick by someone or something [and] stick with someone or something
to support someone or something; to continue supporting or committing to someone or something when things are bad. • Don’t worry. I’ll stick by you no matter what. • I feel as if I have to stick by my brother even if he goes to jail.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, stick to. Remain loyal to, as in The brothers said they'd stick by one another, no matter what, or Phyllis promised to stick to Bert. This idiom derives from stick in the sense of "adhere." [Early 1500s] Also see STAND BY, def. 4.
American Heritage Idioms