mumraa
That’s a shocking thing for a friend to say, frankly his/her attitude borders on the ungrateful, and quite frankly is not deserving of your kind invitation. I experienced something like this briefly but not as harsh..
You’re not doing anything wrong - as you rightly point out, its quite legal so long as the costs are equally split. I also share costs with other flyers, its the only way to hour build.
I am lucky because I have an excellent PA28 share that’s cheap on fuel. As a rule, I only take non-aviation enthusiasts as part of the usual 'pleasure flights' that every new PPL seems to have to do. To be honest, these pleasure flights are hardly taxing (flying round their house etc), and probably isn’t the best form of hour building.
I tend not to invite other guys from my share too often because they'll want to fly the return leg, hence hour building suffers - may seem selfish but us wannabes have an agenda! However, these guys are normally more experienced so have something to offer.
Instead I invite friends (stress invite, not force or nag) who are student/new PPL's to share the workload and are quite willing to split the low hourly costs. Most see it as a bargain because they spend over £100 with instructor and plane for PPL training, but flying with me costs them a fraction of that. I must iterate that I am NOT attempting to act as an instructor on these flights.
Perhaps you should give it a try. Its great if they have a few hours under their belt because they can normally fly straight and level, leaving you time to really improve navigation technique, radio calls, in flight progress etc, in flight checks etc etc. Makes a better pilot of you in my opinion, drums it home.
Best of luck,
Bodie