I feel very torn in replying to your question. My ex and I have a decent relationship and luckily, we live in the same town. When my son hit puberty, he wanted to spent more time with his father and less with me because I'm "too strict and treat him like a little kid" (his words). We worked it out by letting him go to a school near his father's home...I drive him across town in the morning, he goes to dad's after school (dad gets off early) and then dad brings him home at night. I am still the "bad guy" who makes sure that homework gets done, says no to activities like going to midnight skating and force him to do chores, etc. But dad is more and more involved. Dad still pays me c/s since I still buy his clothes, pay for lunches, lessons, allowance, medical expenses, etc. But, I now let dad claim him on taxes because he spents so much time there. We are real flexible about him spending week nights at dad's if he wants to stay late at a friend's house on that side of town, or switching weekends if either of us is doing something "fun" on the other's weekend that he wants to join in on. As he gets older, he is spending more and more time with dad but it's ok because the ex and I talk over all major decisions.
If you lived closer, I would recommend this type of situation since it allows the child to leave mom when he is feeling independent and retreat back to mom when he needs to be babied alittle. is there any chance of you moving back to that area?
Thirteen is a funny age when one minute they are almost adults and the next minute they are little kids....think long and hard before you uproot him on his whim.
Oh, one small aside. In case you have the impression that my ex and I have this wonderful relationship and that is why our arrangment works, I should tell you that he is now living with my ex-best friend and he doesn't approve of the man in my life. So, it isn't all sunshine and light. However, we both agree that our son comes first and we have to act like adults when it comes to his welfare.