Benny Blanco felt like he was fiancee Selena Gomez's "personal journal" when writing songs for their upcoming album

Speaking on Spotify's 'Countdown To I Said I Love You First: Selena Gomez and Benny Blanco In Conversation', the 'Only Murders in the Building' star noted they would chat in the mornings but never had a conversation about the record.

She added: "It was very, 'this is on my mind,' 'what is that,' 'how does that make you feel?' kind of thing."

Benny admitted: "Yeah, I felt like your personal journal.

"I was just, constantly writing whatever you said, wherever we were.

"Sometimes you'd be saying something, like, really important, and I would - I didn't know if you even realised - but I would open my phone and be like, 'F***, that's such a good line for a song.' "

Selena confirmed she had noticed her fiance taking notes.

She added: "But I was very - you know me. I could just sit there and talk...it didn't bother me, if that's what you're asking."

Elsewhere in the interview, Selena and Benny, who were friends for a long time before their relationship turned romantic, recalled the first party they attended as a couple, which was hosted by her pal, pop icon Taylor Swift, after "some awards show".

They were the first ones to arrive but it left Selena feeling "mortified" and uncomfortable.

Recalling the moment, the 32-year-old singer said: "As a couple, we went to Taylor's [Swift] party after some awards show.

"I don't know it was kind of cute, but I was mortified.

"Apparently, cool people don't show up to parties on time."

But Benny - whose real name is Benjamin Levin wasn't surprised by their punctuality.

He added: "We're the first people at every single party when I go with you. You show up when like my mother shows up to a party."

Benny knew he wanted to have a baby with the 'Calm Down' singer after they first locked lips.

He fell so madly in love with her after their special smooch, that he set out their future in his head.

The 'Moves Like Jagger' producer revealed: "I knew right after we kissed, I was like, 'Oh wow. I'm probably going to marry this person.'

"Well, I didn't say marry but I was like, 'I'm probably going to have a baby with this person.'"

A flattered Selena simply responded with: "So cute."