Now for Borderlands I think the halfway point is “New Haven” correct me if I’m wrong. However what would you think is the halfway point for Borderlands 2/Pre-Sequel?
Everytime I reach New Haven, I always let out a breath of relief knowing…ah I made it 
I’m known for restarting alot just to flip-flop on classes lol. That’s why I’m so relieved that I stuck with that class I currently am <3
Sanctuary the second time.
I tend to think that Where Angels Fear To Tread is considered the halfway point for BL2, considering there are nearly as many side missions to do as there are main missions left (I’m just guessing about the number- it just seems like there is 
) …
Sanctuary or Where Angels…
Yeah I’d agree with the guys that are saying Where Angels.
There are in fact only three main missions after Where Angels fear to tread, so I’d have to agree with @Gulfwulf here. Side missions don’t really mark a halfway point, since they’re not linked together like the main story.
Inserting it into a classic story structure:
1st Act: “My First Gun” to “The Road to Sanctuary”
2nd Act: “Plan B” to “Where Angels Fear to Thread”
3rd Act: “Where Angels Fear to Thread Part 2” to “The Talon of God”
Side missions don’t count, since you can choose when to do them. The halfway point is returning to Sanctuary after it’s already in the air, as a lot of other people here said it. It’s actually placed almost exactly at the halfway point (story mission 11 out of 19) and it’s the natural “breathing point” in the game. “Where Angels Fear to Thread” is a major turning point in the story, including the deaths of Roland and Angel as well as Lilith’s kidnapping, but storywise, it’s already the beginning of the end.
GutOnez has it.
In BL1, getting to New Haven was the end of the first Act. I’d say the end of the second Act is when you fight Baron Flynt, or thereabouts.
In TPS, it’s probably Act 1 up until Concordia and Act 2 up until Getting back up to Helios.
Stories generally have the three phases.