If I go to my boyfriend's wrestling match will it mess him up?

I want to be a wrestling trainer/manager/mat maid... whatever you want to call it... for my school's wrestling team with my friend who's already done it for 2 years and likes it. I'm dating a wrestler now and he is never assertive with me until I mention being a trainer and he flips out. He does NOT want me a trainer because he says it will mess him up. Will it really mess him up like in matches or something if I'm there?