I have 7 years practising Wing chun, it took me 5 years to get an "intermediate" rank ( officially we don't have ranks at all just people who have more experience/skill than us), when we train technique we have a partner, back then when i was a beginner everytime we had a different partner to avoid getting used to one person size/strength/speed etc...
But now i don't know why it was my sifu decision to change this, now we have fixed partner to train, the issue is mine partner sucks in the sense he doesn't practise more than we do in that class nor he exercises, so he always get tired way too fast after just warming up, also he gets distracted too easily. He barely has 2 years of training, sure there is people who has more skill but not him, he confuses the names of the techniques, still lacks of coordination and worse of all i don't see any motivation from him (which would explain the slow progress).
I tried to help him to get better at it, but no result if he's not willing to do it. Also i don't get better either.
How i can address this to my sifu being tactful?