Everyone responds differently to the various exercises available and this is a major factor when devising the best training routine for you. When training by yourself you can work on the exercises that you enjoy and get the best results from. For example, not everyone gets good gains from the bench press, some do better with dumbbells instead. If you are doing certain movements just to fit in with someone else you could be robbing yourself of maximum chest development.

It's great if your training partner is on the same wave length as yourself with regards to training style preference, but it could be holding you back if you don't share the same training beliefs, dedication and intensity. If this is the case, either changing training partners or training alone could be the key for you to start making some progress in the gym again.