This sentence is a lyric, which comes from the song "Fall in love with a romantic man" by Mai. The lyrics describe a person falling in love with a romantic person. They love each other in the Lord.
"Peter loves this" in the lyrics can be understood as "love", which means that two people love each other; "We love each other in the Lord" can be understood as that we also love each other on the level of faith or spirit.
Generally speaking, this lyric expresses romantic love and friendship, as well as mutual care and support.