Oh, I don’t think people thinking it’s a phase is something to worry about, the show spent too much time to emphasize how much Sterling was pursuing April despite all the obstacles. It was clear she was upset about her and as she said, it was “so easy” with Luke, she wanted to go back to those easier less complicated times.
That doesn’t mean we might not have some more Luke next season, possibly even a weird messy triangle where both April and Sterling seemingly go after him while wanting each other, these writers aren’t gonna go for the simple route. The only good thing about that is at least it’s a binge so you won’t have to go week by week to see it all unfold until they fold and go back to each other. 😛