THE Veronicas took lust at first sight to No.1 in Australia this year with In My Blood.

Their follow up single, On Your Side, is a mature reflection on the tricky but rewarding business of staying friends with your ex.

The lyrics document a break-up that’s weathered everything from supportive public transport vomiting to t-shirt theft as a memento.

The lyrics “I remember the night when you packed all your bags in the doorway, said I don’t want to fight you can leave but remember I’m always on your side…” discuss coming out the other side without bitterness.

The Veronicas’ Jessica and Lisa Origliasso channelled intensely personal experiences into the song – which is also the shortest Veronicas single to date at two minutes 50 seconds.

“You can spend all this time with someone, be vulnerable and raw with them, and then when it’s over in many relationships it’s like that person never existed,” Jessica says.

“That’s a hard thing to accept and understand. It’s something I’ve struggled with in my personal relationships, the idea of unconditional love and what love really is, feeling bitter or sad at another person when it ends. Obviously there’s times you can be so badly hurt that’s not a possibility.

“But if you want your ex to win in life I think that’s the most beautiful place we can come to as human beings and as a partner, to offer our understanding and love. You can come to a place where you say ‘This didn’t work out how we’d hoped, but I still love you, I want you to be happy and I’m here for you no matter what’.”

This mindset is a long way from the venom that fuelled early Veronicas material, or the savaged heart on former No.1 You Ruin Me.

“You listen to our first record and it’s all ‘Fuck you! It’s over!,” Jess says. “There’s not a lot of grace or understanding there. Even with You Ruin Me there wasn’t that perspective of unconditional love. But on this song we really got there.

“You have to really accept a lot when you write a song like this. There was a lot of tears writing it, but different kinds of tears. It was very very therapeutic. Lisa and I really try to implement higher spiritual values in our lives now, and it’s really offered peace and perspective in relationships. It’s a very big message to put into a pop song but it’s reflective of where we’ve reached as women and partners.”

Dropping the tempo slightly from In My Blood, On Your Side was written and recorded in London with UK pop gurus Wayne Hector (Nicki Minaj’s Starships, One Direction’s Steal My Girl) and Jim Eliot (Kylie’s All The Lovers and Two Hearts, Ellie Goulding’s Anything Can Happen) and produced by up and coming Swedish whizkid Ollipop.

The sisters are putting the finishing touches on their fourth album, which has a “heavy Euro electro pop” feel.

They’ve had the luxury of working on the record while In My Blood continues to be one of the biggest singles of the year in Australia, as well as making inroads in the UK, US and Asia.

“Every other time we’ve released a new single the album has already been finished,” Jess says. “So to have a No.1 single as a motivation is amazing. It never gets easier releasing music, you never know if people will like it but to know people really connected with In My Blood and the sound of that song was mind-blowing. It’s given us a real perspective on how to finish this record.”

On Your Side is out now.