This is because you have enabled the fast-forward only option. The thing here is your pull from the branch will create a merge commit in your local git and the fast-forward only option doesn't allow creating a merge commit at the time of pull.
In the case of a big team, You will end up rebasing and resolving conflicts lots of the time and for each and every commit coming from the pull.
I suggest you remove ff = only line from git local config file.
$ cd to-my-project-root-dir
$ nano .git/config
[pull] ff = only // remove this line rebase = false