Sometimes children feel lonely owing to they do not have anyone to play with.
Sometimes children feel lonely owing to the fact that they do not have anyone to play with.
Sometimes children feel lonely because they do not have anyone to play with.
Owing to means ‘because of’ and is followed by a noun or noun phrase: ‘The flight was cancelled owing to bad weather.’
Before a clause with a subject and a verb, use because, since or owing to the fact that. However, because is usually simpler.
See DUE TO