Headcanon that as Spider cares little for Jake and Neytiri then he lets on. One day, maybe after the 2nd movie took place, Jake just tells Spider he accepted him as one of his own and pouring out his heart to Spider.
And Spider just hits him with a "Okay, but I have never accepted you or Mrs. Sully." And just states matter of factly that he only cares for the Sully kids because they had never treated Spider like dirt. Maybe when he was little, he wanted a mother or father figure in the couple but he could only be let down so many times before he gives up on them and stop caring for them.
Just Spider tearing Jake a new one as he states that the only ones to matter to him in the Sully family are Neteyam, Lo'ak, Kiri, and Tuk. Mo'at also means a lot to him too. But how both Jake and Neytiri are on a similar level as Quaritch but for different reasons. It didn't hurt Spider when Neytiri cut him and he 100% believes she would have killed him that day, he expected it from her. Spider tells Jake that suddenly opening your heart, or your heart "always" being opened to him will not erase the years of hate and disrespect.
Spider let's it be known that he would never forgive Neytiri and Jake for causing the rift between him and Neteyam, and using their eldest son's people pleasing nature to their own benefit. Neteyam is gone and Spider will never get those years back and he blames Jake and Neytiri for that.
Spider holds little care for the couple and if Spider never saw either of them again he would be fine, it's only the love that Spider has for their children is what keeps him with putting up with their bullshit.
After saying all this, Spider just walks away without looking back, uncaring of a response, let alone an apology. Leaving Jake, who is still as a stone.