Revelation 14:10 The same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb
Now you cant get any plainer and clearer then that.
As for 2 Thess 1:8-9. In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ: 9 Who shall be punished with everlasting destruction from the presence of the Lord, and from the glory of his power.
This isn’t saying that there is eternal separation from the Lord, its saying that they will be tormented from the presence of the Lord. Its like saying… my eyes hurt from the presence of the bright summer sun. Does that mean i am away from the sun? No. It means i am in the presence of the summer sun that my eyes are hurting from. The sun is causing that hurt because i am in the presence of it. Not away from it. Therefore making Rev 14:10 correct. Otherwise they would contradict.