Unfair Game actions?

I luv dis game but I don't understand y some game actions re not fair like when am winning ND dominating against a weak team then they have a comeback (while am still dominating) and then I move forward and equalize and then 90+3 (when it's just 1min added) they score.y wud I struggle against a weak team and then still with a strong team and yet my team is strong.i don't did is justified