You can fix that loose pool liner with a simple patch.

Yes, you can fix it yourself if you catch it early.

The liner pulling away usually means water got behind it or the coping is loose. First, drain the water level to below the pull-away section. Let the wall dry completely — a wet patch won’t stick.

Use a pool liner repair adhesive (the sticky goo in a tube) and a patch of matching liner material. Apply the adhesive to both the wall and the liner, press it together, and hold for a few minutes. Some people use a weighted object or a scrap of wood clamped against it to keep pressure while it sets.

If the bond fails or the liner is stretched out, you might need a professional to re-seat the liner. But for a small pull-away, a patch is worth trying first.

Don’t let it sit — that gap will only grow, and you’ll be replacing the whole liner.