What is the ruling on being infatuated with one's aunt, and is this considered like thinking about a foreign woman (non-mahram)?

Incest is one of the gravest sins. To avoid this temptation, do not go to your paternal aunt, and do not speak to her except out of necessity. Do not be alone with her, and do not look at her with lust. Ask a trustworthy female relative to caution your paternal aunt to stop the provocative behaviors. If she does not desist, then shun her.