Joe Jonas started dating Game of Thrones actress Sophie Turner in 2016; they got married on May 1, 2019. He wrote this song to tell Sophie he'll always be there for her.
I thank the oceans for giving me you You saved me once and now I'll save you too I won't hesitate for you
Joe is saying he will never ever hesitate to take any pain she is feeling and put it on his heart.
Joe told Apple Music: "This is an important song. I wrote it for my significant other, Sophie, and it's one of those love letters that you write to your partner saying, 'I'll be there no matter what.'"