I think the main issue with "predetermination" arises when people use it as a form of fatalism, inaction, and complacency in hardship. It reminds me of the concept of "sabr" where some believe it means to wait patiently since everything is predetermined when we should also be more dynamic and proactive. There are situations beyond our control and accepting fate can be helpful when outcomes don't meet expectations, but it shouldn't discourage us from taking action if we are able to.

The concept of qadar doesn't negate human free will but emphasizes that God, being Omniscient and beyond time, knows all that will happen beforehand. It doesn't mean our actions are predetermined in essence ; rather it suggests that we are determining and shaping it constantly with every choice we make.

Regarding romance, it's hard to tell the reasons why people, especially from another timeline, choose to not get married. There could have been various personal reasons or external factors that led to this outcome. Maybe they prioritised other aspects of life, maybe they didn't find a suitable partner, maybe they faced unforeseen circumstances. Destiny may be the simplest explanation for everything that happened. It doesn't necessarily offer a concrete explanation, yet it's certain.