A phrase used when a situation has reached a certain state — meaning 'given that this is the case' or 'now that it has come to this' — often introducing the next decision or action.
こうなると、もっと積極的に行動するしかない。
Given that this is the case, we have no choice but to act more proactively.
予定が大幅に変わってこうなると、別のプランを考えたほうがいい。
Now that the schedule has changed drastically, it's better to consider another plan.
こうなると君の判断が試される場面だ。
At this point your judgment is being tested.