For one thing you forget that the adoption was symmetrical. Not only John takes her with his own, but she adopts him.
Second, "with his own" together with "disciple Jesus loved" indicates the body of disciples.
Third, there is nothing there to indicate that His relationship with His mother was at an end. He was going to be with a thief in Paradise, but not His mother?
That's an inference. It's not clearly in the language as far as I can tell. It's a tolerable, reasonable INFERENCE, ASSUMPTION, EXTRAPOLATION--BUT AN ARBITRARY ONE. The text does not require it.
Second, "with his own" together with "disciple Jesus loved" indicates the body of disciples.
WOW. That's a stretch. More wild, arbitrary, inference, assumption, extrapolation--even brazenly reading something into the text that's not there.
Third, there is nothing there to indicate that His relationship with His mother was at an end. He was going to be with a thief in Paradise, but not His mother?
Ahhhhh . . . but great discomfort at someone else's inferences, assumptions and extrapolations. Clearly it's not a two way street! LOL.
I did NOT say His relationship with His mother was totally ended period. Please avoid putting words in my fingers.
I said that the special Son/Mother relationship [function] was ended. That's a very plausible inference. I consider it the MOST plausible inference plainly there in the text.
Somewhat like an elder brother going off to a distant land or planet . . . trusting his mother to his next younger brother--knowing the oldest son will never return and their mother/son relationship and function is now at an end.
Being with Mary and the thief in eternity is a different issue. The handoff to John of Mary was for the rest of this life. Of course Christ is with all believers in eternity. No biggy except for the awesomeness of eternal life and life eternally WITH HIM.