Grandchildren
Long separations were always harsh on Monica. Khan also suffered without her, but she had it worse. Khan was the center of her life, her only source of happiness, and she had grown reliant on his presence.
Nevertheless, Monica knew she couldn't monopolize every second of Khan's life. Both of them had duties to attend to, especially him. Khan needed to excel in many fields to eliminate the curse that afflicted him at night, and Monica wouldn't let her affection hinder him. She would rather suffer alone than prolong Khan's pain.
Ideally, Monica would help with Khan's quest, but her options were limited. Her parents had already disclosed most of what they knew about the topic, leaving only financial and political support at their disposal. That was still huge for Khan, but Monica wanted to do more.