Not to be an intense larrie BUT...
Let's break down the lyrics of DLIBYH:

On our way to Twenty Seven
Got a place on the other side of London
Doing better
Doing better++

"On our way to Twenty Seven". Twenty Seven is a hotel in Amsterdam. Let's remember what happened in Amsterdam++

According to my research... Louis and El went to Amsterdam for her bday (July) and he took her to a gay bar. ++

On August 27th of the same year, Louis tweeted a middle finger emoji and said that "some industry shit" was pissing him off.++

Louis also released a snippet of the song 'Always you'. Let's check the lyrics:

I went to Amsterdam without you
And all I could do was think about you
++

He also tweeted that he had been in Amsterdam a month ago (July). So, if the song was about El, why would he say that he went to Amsterdam without her? ++

Then, damage control kicked in:
+++

"Got a place on the other side of London"
Okay, I suck at geography and idk anything about London so if you see I'm wrong please tell me and skip to the next lyrics haha++

This line could refer to where Louis lives nowadays (I have no clue of where that is) or it could be the setting of two hearts in one home... yes, Princess Park.++

According to the media ‘The Dome’ is where Harry and Louis lived. That is located in Princess Park Manor, in Barnet. Barnet is a suburban London borough in North London, England and it forms part of Outer London.
So, is this "the other side of London"?++

I know you left a part of you
In New York under your bed in a box
But you're
Doing better
Doing better
++

As we know, it's rumoured that Harry was in New York when he received the news that his stepfather Robin was terminal. ESNY describes how he felt dealing with the death of Robin, it was REALLY hard for him & that's why he "left a part of him in NY under his bed in a box"++

It comes and it goes
We're driving down a one-way [one direction] road
To something better, something better
+++

This describes being in One Direction, and literally going in ONE DIRECTION (it's kinda funny ik). We all know how they had to follow the rules in 1D and how big it was for all of them. But let's hear Harry say it:

It also reminds me of what Louis said in this interview: They'd be talking about what they were about to "go into" being this "something better".

We all know what the rest of the song talks about (and it's my favourite song) but those lines where the most important ones for this theory. ++

If you made it until the end of this thread thank you for reading! I have a theory for the lyrics video too, so tell me if you think I should post it! xx

Oh, and for all those who are saying Louis didn't write this song: