The song "Youngblood Mashup" by Alycia Marie is a medley of different songs by 5 Seconds of Summer. Each section of the mashup carries a particular theme that explores the ups and downs of a relationship.

The first section of the song "Youngblood, Babylon" reminisces about a past relationship where the couple shares a deep love for each other. The protagonist of the song surrenders everything to the person they love, hoping that the love would last forever. However, with time, the relationship fades away, and the protagonist is left with memories of how things used to be.

The second section, "Better Man, Talk Fast," focuses on the struggle of letting go. The protagonist of the song is having difficulty coming to terms with the end of the relationship, hoping that things will change. The protagonist is also aware that they need to move on, but this is easier said than done.

The third section, "If Walls Could Talk, Talk Fast," explores the secrets and lies that exist in a relationship. The protagonist wishes that the walls could speak and highlight all the negative things that happen in the relationship. However, they also acknowledge that the relationship has already suffered enough and that it would be best to move on.

The fourth section, "Lie to Me, Why Won't You Love Me," depicts the hopelessness of a relationship that has ended. Despite seeing the person they love with someone else, the protagonist can't seem to let go of the idea of being with them. They are still holding onto the hope that they could be together again.

The fifth section, "When You Walk Away, Moving Along, Want You Back," further develops this theme of holding onto the past. The protagonist is still reminiscing about the good times they had with their ex-partner and is skeptical about moving on. They are uncertain about being able to find someone like them and often wonder if they are thinking about them too.

The sixth section, "Empty Wallets, Best Friend, More," is about trying to find happiness after a broken relationship. The protagonist's sole focus is on moving on and finding happiness in any way possible. Though they still have a desire to be with their ex-partner, they are more focused on finding inner peace.

The seventh section, "Woke Up in Japan, Meet You There" highlights the loneliness that comes after a relationship has ended. The protagonist feels lost and abandoned, and all they crave is to be with their partner again. They look back on the good times they had together and wish to rekindle their relationship.

The eighth section, "Monster Among Men, Woke Up in Japan, Meet You There," takes a darker tone, driven by the feelings of regret and self-loathing. The protagonist feels like they were a monster in their previous relationship, leading to its downfall. They feel that they will never be able to find someone like their previous partner.

The ninth section, "Valentine, Midnight," depicts the passion and intensity that comes with a new relationship. The protagonist is willing to do anything to be with the person they love, no matter what it takes.

The final section, "Ghost of You, Lie to Me," is a retrospective of a past relationship that ended before it had a chance to blossom. The protagonist wishes they had known better and not been so naive about love. They are aware that the relationship they had would never be the same again and that they must learn to move on.

Overall, "Youngblood Mashup" explores the many emotions that come with a broken relationship, with each section offering a glimpse into the complexity of love, loss, and healing.