Reunion between a guy and the girl he loved and left

[BWTraveller]

I recently picked up Iris Zero and, like so often with me, a spot made me desperately want to see something that I suspect won't happen. This time, what I'm looking for is stories (anime/manga/LN) where a boy falls in love with a girl, but he winds up leaving her in spite of this love, and later he is shocked to find her standing there in front of him again. It doesn't necessarily have to be geographical distance, it can just be him finding ways to make an emotional and social distance between them, transform her into a stranger in the crowd, and then suddenly put in a situation where he has to legitimately face her again.

I'm most interested in stories where the boy believes he's doing this for the girl's own good, perhaps keeping her out of some sort of danger or away from painful experiences, or stopping her from being persecuted on account of him, but it's also fine if it's circumstances beyond his control or even a matter of weakness/cowardice on his part. Big bonus if the reason they meet up again is because the girl decided to go after him, but just as fine for them to just suddenly find themselves momentarily together again. Also bonus if the girl loves/loved the boy in return, and at least one of them has some feelings still.

I'm OK with almost any length of separation, though I'd like more than a month but not so much that they'd both be firmly established adults by the time they reunite. The extra-long stories have their charm as well, but I just like to see them still deciding their futures when they reunite, so that even if there isn't any lingering love and no new love developed, at the least the two can continue making their future having gained closure on the former relationship.

Best example I can think of is a scene from the later half of the manga Ginen Shounen:

Spoiler:

Matataki has spent quite some time trying to win his childhood friend Mirai's heart from his rival Koda, to change the pictures that show both her future in a relationship with Koda and Matataki's future death. Instead of fading though, they have grown clearer and more certain. At that point, Matataki moved with his father to Spain in hopes that at least he'll die someplace far away where Mirai will never even hear about it and he can spare her some tears. More than a month pass, less time than I'd like but sufficient, and Mirai finds out about the future pictures. She immediately takes off for Spain with nothing but a backpack and the location of his school, somehow manages to find/be found by him, and jumps into his arms, reproaching him for just running away and never telling her about his struggles, and ultimately convincing him to return and face this future at her side.

Finally, I'm also OK with a gender-reversed version of this, where it's a girl who leaves the boy she loves.

[SeijiSensei]

Asatte no Houkou - Couple moves to America, but she returns to Japan. Then she encounters her ex-lover when she befriends his younger sister. This is a "body-swapping" story, though, not one that focuses on their relationship.

[NervZero]

For some reason I thought of Claymore right away...

I loved this anime not sure if it is what you are looking for or not...

https://myanimelist.net/anime/1818/Claymore

[Fairy Water]

Mars Daybreak... it's fit your requirements perfectly except the fact that I don't really into this series... maybe u will?

Kemono no souja erin.
The girl and her love interest are often go their separate ways and when they accidentally meet... XD

Charlotte.
Well it's happened at the end of the story and the ending was rush af... but check it out!

Please save my earth.
Master piece amongst master pieces. Don't give in to the art of first few volumes, the story itself is great and beautiful. There are many kinds of separation and reunion.

Mushoku tensei (LN/WN)
If you don't mind the harem thing. The protagonist only married three girls and they're all his important and treasured people. They all have the same separated in childhood then meet again as grow up. It's a great novel tbh so for the first time I agree that he could marry three women because they're all deserved it.

[SeijiSensei]

The roles are reversed in the first installment of Otona Joshi no Anime Time. She left.