He【主语】// is 【系动词】//friends 【表语】//with me【对象状语】.
备注:这里用复数表示“朋友关系”更多例句如下供参考
I still wanted to be friends with Alison.我还是想和艾莉森做朋友。
We remained good friends.我们一直是好朋友。
备注: a friend of mine=one of my friends(我的一个朋友)
He is a friend of mine.=He is one of my friends.