Proactive Decision Making

You are right. This is all part of Risk Management. The project manager needs to work with the team and the sponsor/stakeholders to identify potential risks. As we all know Risk Management continues throughout the project to identify any potential issue and to come up with mitigation strategies.
Additionally, the Project Manager should be proactive in regards to opportunities.

Project Manager's primary responsibility is to make sure all issues impacting the project constraints are resolved appropriately.
They may identify some issues , but issues , like risks can be identified by anyone who is associated with the project , be it , the Project Management team or any of the stakeholders.
The Project Manager should be a fact finder and should be capable of gathering and producing all the relevant facts regarding an issue to the stakeholders and encourage a collaborative resolution wherever possible.
The Project Manager is more of a facilitator than a decision maker. A Project Manager should , through frequent communication with stakeholders , identify the factors that may lead to a project delay.
Regarding making tough decisions, as long as the project manager can understand the situation and recommend the path of least impact to cost, quality, schedule or scope , there is no need to be afraid.
As others have said, we are human beings so we just have to pick up the pieces, gather learning from the experience and move on.

It's difficult to be proactive on issues. By their very nature, issues are questions or situations that require decisions and unplanned actions.

If we could be proactive on issues, decisions would be made and activities added to the schedule.

You could try to avoid all issues but than can be an expensive endeavour. I think as project managers, we have to balance planning against paralysis.

Proactive action is other done using risk management. Once at it become an issue it is no longer a risk, and generally required immediate action.
You can be proactive during risk management and prevent some issues.