No it's totally understandable! I've treated them less serious in the past (I wouldn't give updates, I'd usually just surprise them and they'd do the same with their half) but now I do treat them like commissions when I take them.

I only make trades with good friends now because I've been screwed over once or twice and it's just not worth it sadly. I wish more artists did treat them like a serious thing. Yeah it's fun because you're both drawing something for each other but it's basically the same as a commission.