One way to possibly curtail some of the bouncing back and forth is to not include him in all of your activities w/you and your son. Maybe one of the reasons he's bouncing back and forth is because the ow is busy or tied up w/her own family and he feels lost w/o the attention (and/or distraction) he's getting from her, so his focus is back on his own family for a short period of time.
I think you need to try to focus on you and your son and let the chips fall where they may w/him and the ow. The more you raise the issue w/him the more determined he will be to save/protect/defend the ow.
Sometimes, if you sit quietly, the answers will be revealed to you. Yes, this really does work. Step back, allow his little love interest to fizzle out on it's own.
Keep the focus on you, your son and your life for now.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
