So here is my issue.
having a girlfriend is not the same as being engaged or married.
there is nothing ethically or morally wrong in letting this run its course.
just do so with your eyes open
I`m wondering how much younger he is than you? Could he perhaps be looking for your advice? Just seems strange that he would show you gifts for another woman if it was you he was interested in.
Men/boys can be interested in women for things other than a sexual/romantic relationship.