I can't play piano when I'm just a little stressed?

I am 16. I usually LOVE playing piano (classical, romantic era). I'm in lessons and have developped an impressive, relaxed technique and I really enjoy and value classical music. But whenever I am just a little stressed, my technique totaklly crumbles and I can't play my music or even practice right and relaxed. I just stressed me out even more trying to relax and get back my technique. Is this normal? Like I can only play normally and freely and with emotion when theres no stress. It ticks me off.