This series only has commercial value, it was created due to fan's responses, but really, it doesn't have that much deep value.
I loved Until We Meet Again, the story was interesting, and the music was top tier(which Between us completely ruined for me, the music effect are the most annoying thing in Between us, I really don't understand how their music got that much worse).
In UWMA the main leads were a bit too cheesy for me and without the second leads it would have been overall an ok series. Because of Team and Win it became a great one.
Team and Win really shined in UWMA, they brought to the table what Dean and Pram didn't and they really balanced the whole series. If they gave them a bit more screen time in UWMA they wouldn't have needed this series and it wouldn't have ruined them.

The plot in Between us is excruciatingly slow.

From the eight episodes I have watched, this is what has happened:

-Team and Win had a one-night-stand on their first meeting
-Team goes to sleep to Win's room basically every night
-Team is traumatized because he accidentally drowned someone when he was young.
-Win has lot of family problems

The same thing happens every episode: Team "rejects" Win, neither of them can figure out their feelings for each other, Team has a bad dream- with a flashback- and Team goes to sleep to Win's room. And most of this information we already knew from the prequel.

Honestly, the whole eight episodes could have been only two, which makes me feel like if they gave them enough attention in UWMA this series wouldn't be necessary.
It's like they are exploiting this relationship to the maximum for profit but there's not that much to give.

Also why so many second-lead couples? I don't care about them and they take a lot of screen time