Paul chastised the Thessalonians for thinking they had missed the Rapture.
He did not deny the Rapture (which he discussed in 1st Thessalonians) but explained certain events needed to occur first, like the apostasy of the Church.
I don't see anywhere that the Thessalonians were aggrieved that they thought they missed the "Rapture". I see where they were wondering about the return of Christ and our gathering together with Him (2 Thess 2:1). I see where lawlessness was already at work in Paul's day (2 Thess 2:7). And I see where the Lord will slay all those who did not believe at His appearance (2 Thess 2:8-12). I don't see Paul mentioning anyone being "left behind".
BTW-I also see where "God will send upon them a deluding influence so that they will believe what is false, in order that they all may be judged who did not believe the truth, (2 Thess 2:11-12)". One has to wonder if God is sending a "deluding influence" how this will affect their ability to understand the Rapture and what is precisely the point of the Rapture?