Very tricky. I have pretty much the same situation with my DS. It started in nursery and continued through reception. As parents we care deeply about our kids emotional well-being but I don't think schools have the resources to focus on individuals to this extent. This won't go away, however, and it is likely to become more sophisticated as the kids get older. If I were you, I'd speak to the school because they'll be more likely to keep an eye on the situation if they know you're interested. Good luck!
I would suggest you just tell your ds that he has not got to be friends with boy 3. You should be able to explain to him that he can make friends with whoever he wants and to just instill in him that he can in fact tell boy 3 to go away. I advised my boys to say "I don't want to play with you, as you keep getting me into trouble".
My ds is in reception. He's just 5. He made friends with 2 boys and they go around in a three. One is quite quiet and sensitive. My ds is boisterous, sporty, fairly confident with friends, competitive, is doing well academically. The third boy is more like ds, and they clash what seems like All The Time. Ds was coming home frequently saying 'boy 3 is being mean to me' etc. we brushed it off I'm afraid to say, partly because in the morning they'd run to each other and play! However as time has gone on they've argued more often. On one occasion the boys mother has rung me to say her boy was upset because ds was 'nasty' to him. I spoke to the teacher and she said it was nothing, just a silly falling out. I talked to ds and he seemed frustrated and said it was the other way round. Dh and I brushed it off as typical 5 year olds (and poor boy 2 always seems stuck in the middle!)
But lately, I've become concerned. Ds's teacher called me in to say boy 3 has upset my ds by stealing from another boys lunch box and then blaming ds so he got In Trouble. The truth eventually came out and the teacher got out of ds that this boy is often mean to him.
I've also witnessed them together on 2 occasions recently and they'll be playing, but then boy 3 will run to his mum blaming my ds for things he just didnt do, or sort of accidentally did in play - eg boy 3 spilt his drink over ds, then blamed ds for it and said he made him do it on purpose! Also he says things like 'you've got to go home Now and boy 2 and me will play without you' and 'ill get a bigger ice cream than you because mrs x likes me better'.
All low level stuff, but i can see it must be upsetting for ds and I feel bad I haven't taken him seriously before, I don't know what to do about it. I want to tell him to ignore the boy but he says he just keeps following him then. I don't know what to advise him to do for the best. The boys mum seems oblivious, or blames my ds because she has her son coming up saying my ds did x to him or whatever. I just don't know - what can I say to ds if anything, and whether or not to say anything to the teacher!
Please help. My ds is behaving badly at home and I'm sure this has something to do with it.