Hello everyone!

I'm looking for a specific shoujo (or josei?) that no matter how much I looked for, I could't find.

What I remember:

The protagonist likes a boy, but doesn't get along with his best friend (a short boy).

One day she sees the boy she likes kissing (or something like that) her older sister.

A lot of bad things happens as the boy really loves her sister, but her sister really loves her and guilt all over.

She've got depressed almost jumped from a high place.

She then finds out the short guy (the best friend of the guy she likes and the real ML) kind of traveled time to stop her suicide. Is his time, she suicided and then he studied for a long time until he developed some kind of tech to go back in time. Since then he traveled many times, but so far, the changes he made never stopped her bad ending.

They travel a lot. She travels, the boy she likes travel, her friend travels...

In the end she falls in love with the short boy, but he forgets everything, so she starts her quest to make him fall in love with her.

Thats it (hopefully I didn't remind anything wrong)! Initially this manga looks like any other shoujo and I don't really thing the "time travel" is described in the summary, but the plot twist left me amazed. Sadly I lost the name of the manga, so I hope someone can help me find it!

maybe Henyoku no Labyrinth

That's it! Thank you very much =D