 If you liked
Steins;Gate
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 ...then you might like
Utsuro no Hako to Zero no Maria
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In both light novels, the protagonist has to suffer through repeated situations where their close ones are endangered or even die in attempt to fix it and save them. While Zeroth Maria has time loops, Steins;Gate has time travel.
The first volume of HakoMari, is nearly identical to Steins;Gate. They both are highly psychological and focus on a protagonist stuck in a time loop, ending with an unfortunate event.
HakoMari differs with focus on supernatural elements, while Steins;Gate focuses on scientific elements.