Sounds like the girl is a control freak and maybe he would even like to cut ties with her but doesn't know how...once he gets out of this relationship, he may be leary to get into another one.
Also, you might want to see what he is "searching" on the internet...it may be more than emailing his girlfriend. It's unfortunate that you can "google" anything these days. One of my daughter's friend told her that if you just google someone's name that they will come up on your computer....I had to tell you that you just can't google anything or you might get more than you bargained for....most of it being inappropriate for her age/eyes.
I have an 11 yr old girl so I'm kinda of in the same boat.
She is in the 6th grade which is considered "middle school" where she is....just get ready because all of the sudden kids go from innocent to knowing every cuss word in the book and using them to try to look cool! My daughter and I are shocked at the metamorphosis her classmates have gone through just in the 2 1/2 months since school started! She is now trying to convince her classmates that they don't have to cuss to be cool!
She too had a boy she "dated" for several months in 5th grade but that consisted of seeing each other at lunch time in the cafe. She decided that he was very controlling of her so she "broke up" with him before Spring and hasn't tied herself down to anyone else since.
She does not have email access and didn't have a phone at that time--she has a phone now but can only call family and girl friends or the phone will be taken away.
I tell her that she is "not allowed" to have a steady boyfriend and to "blame it on her parents not allowing it" if the boys give her a hard time.
I tell her that she shouldn't tie herself to "one" boy for the next 10 years of her life because then if another comes along that she likes then she can't act interested in them if she is tied to one.
I talk to her all the time about the qualities a male should have before she should even consider "dating them". They are: Christian and Attend church, have Christian parents, kind, considerate, honesty, integrity, not controlling, not insultive, respectful of adults/authority and their peers, respectful of others property, do not use bad words or ugly language, funny, witty, hard working, performs good deeds because it's the right thing to do (not for the recognition), stands up for others when a situation arises, etc, etc.
I tell her that God has someone picked out for her that is way better than anyone she could pick for herself and that that boy's parents are grooming him to be a the wonderful Christian mate that he needs to be to make a good marriage partner. I told her that she may not even know him right now and to just see what happens as her life unfolds.
Maybe if you tell him that since he is approaching that age of "dating" that there are certain things he needs to know in order to be a good boyfriend to in turn get a good girlfriend and maybe if he knows the girls are being taught too then he will be receptive to talking with you.
I always use myself or someone I know as examples of whatever I am trying to teach to my daughter. We all learn from the good judgements and mistakes we or others have made over the years.
It's really important for you to try to gain an open relationship with him now if you can. Just be honest and say "okay, here's the deal....." and have that talk. Let him know that he can come to you about anything and that you are a "girl" and can possibly give him insight into a "girls" way of thinking.
Good luck!