While filing for divorce before your spouse doesn't offer significant legal advantages, it does allow you to set the course of the case. By being the one to file, you communicate to the court that you are unhappy with your current situation – and the truth is, doing nothing about a situation you're unhappy with carries its own risks.
Courts generally assume that if a particular arrangement has been in place for a while, it must be because both people agreed to it. So, if you've silently endured something that you thought was unacceptable, the court might assume you were okay with it, which could harm your case. What’s more, if your spouse files before you do, the court might assume that you only started objecting to the situation as a form of retaliation, which could weaken your position.
For this reason, filing first can be a strategic step, especially when you disagree with what your spouse is doing. This act alone can serve as a formal declaration to the court that you're dissatisfied with the status quo, making it harder for anyone to argue that you are acting vindictively.