Are there any decent long stories where Harry Potter is not paired with anyone?I am in no way a celibate,but sometimes I just want to read a story without any romantic element.

Here are some that I have found.
https://m.fanfiction.net/s/11858167/1/
the sum of their parts

https://m.fanfiction.net/s/1962685/1/A-Stranger-in-an-Unholy-Land

a stranger in a unholy land (why, why he has to be with someone in the sequel…)

I don't include those stories with a Harry who has not reached the age for romance.

 

Here are a few - I make no promises about quality!

https://archiveofourown.org/works/19853347/chapters/47015068
The Blood Incantation
Lomonaaeren
Summary:
AU. It’s 1972. Charlus Potter has been part of a secret strike force that managed to put down Lord Voldemort permanently, but at a heavy cost, including the lives of every other single Potter. Desperate to keep his family alive somehow, Charlus summons the ideal heir—and gets a stranger named Harry Potter from another world where the war extended much longer. Slowly, warily, Harry and Charlus become a family.


part one of a series:
https://archiveofourown.org/works/16756768
Fruit of the Golden Tree
Lomonaaeren
Summary:
Thanks to the desperate actions of his wife, Fleamont Potter survived his dragonpox. Now he finds himself awake again in a world where all the members of his family are supposedly dead—except that the Potter family tree tells him that his grandson lives yet. Fleamont sets out on a search for his grandson, and then a quest to keep him safe once he’s found him.

There’s minor mention of a pairing here but not really:
https://archiveofourown.org/works/9555569/chapters/21605777
i won't just survive (no you will see me thrive)
EclipseWing
Summary:
In which James Potter isn't as dead as everyone thought and Harry has a strong mistrust of all adults.
Reconnecting with his son isn't going to be easy, not just because Harry's in Slytherin.

This one is a little out of pocket but I’m a fan -
https://www.fanfiction.net/s/5666734/1/Not-Set-In-Stone
Not Set In Stone by Neurotica Harry Potter u:05-27-2011 - Complete. AU. Set summer before OotP. There's a mysterious new member of the Order of the Phoenix, one that knows exactly how to deal with Sirius Black's moods, who seems well-liked by everybody. And whose story doesn't quite add up. No Slash