IanG

Warm and plausible, well done.

Try 'Father retires to the living room# rather than 'father resigns to the living room'. Resigning refers to quitting a job due to pressure or a crisis, retire can mean leaving a scene or a room voluntarily.
That said, I like your descriptions of nature and the twist at the end is a good one. Keep it up.

Perhaps you could say 'at first he didn't realise the door was ajar,' as he clearly does realise eventually. Nonetheless its good for a first attempt. Your protagonist and his feelings are totally convincing.

Considering how young you are, you evoke nostalga very well.

This is a plausible, relevant story. Well done.

You describe the scene and the change of mood very well.

You evokr the setting very well. I could imagine myself there.

Your narrator's loneliness is convincing and the twist at the end is good. You raise a lot of questions over the 'imaginary' friend but a touch of mystery can be a positive.