They didn't even share any screen time together in Chosen - something they deserved to have more than Bangel if you ask me - so I have no idea if they're back together, cause I vaguely remember Xander calling Anya "sweetie" in Chosen, or if they parted as friends.
Xander's scene with Andrew shows he clearly loves her - the tremble in his lips and voice and his Xander sense of humor when distressed. But it doesn't tell us what they were for each other.