Wouldn't you be happy if a friend told you something like that?
Don't you think you would be happy if one of your friends said something like that to you?
ーWouldn't you be happy if a friend told you something like that?
「もし友達があなたにこんなことを言ってくれたら嬉しくない？」
Wouldn't you be happy if ...? で「もし…なら嬉しくない？」という言い方です。
ーDon't you think you would be happy if one of your friends said something like that to you?
「もし友達があなたにこんなことを言ってくれたら嬉しくなると思わない？」
Don't you think you would be happy if ...? で「もし…なら嬉しくなると思わない？」という言い方です。
ご参考まで！
カナダ 
