Is the heart's inclination or the arousal of desire when speaking to women considered a sign of a diseased heart, based on Allah's saying: "then do not be soft in speech [to men], lest he in whose heart is disease should covet"? And what is the remedy for that?

Whoever finds in himself an inclination to fall into indecency when speaking with a non-mahram (definition) woman, this is an indication of a disease in his heart, either weakness of faith, hypocrisy, or a desire for immorality. Whoever finds this disease must strive against himself, avoid the causes of temptation, hold fast to Allah, and rely on Him to rectify his heart, and ask Allah for protection [from sin] and guidance.