I am aware that there are quite a few posts about these two words on this forum, but after perusing them I still don't think I fully understand the difference.

Could anyone please provide me with some examples where 'relation' and 'relationship' are not interchangeable?

I've abstraced 3 pairs of examples from my dictionary. Please help me pick out one that is stylistically preferable from each pair :

the relationship between poor housing and health problems

the relation between prices and wages

The lessons bear little relationship (=they are not connected) to the children's actual needs.

The price the meat is sold for bears no relation to (=is not connected to) the price the farmer

What relation are you to Jessica?

'What's your relationship to Sue?' 'She's my cousin.'

Understanding the nuances of synonyms gives me a headacheEmotion: crying.

Thanks in advance Emotion: smile
Not that I can enumerate why, but my preferences are:

1. relationship
2. relation
3. relation

Relationship can describe the person someone is dating. Relation wouldn't be used in that context.
Thank you very much Emotion: smile