The Prophet said, "Do not visit women whose husbands are away from home, for the Devil circulates in you like your blood." He was asked if this applied to him also and said, "To me also, but Allah has helped me against him so that I may be safe." [Tirmidhi transmitted it.]
Response: It is not allowed to speak with a non-related woman with any speech that stirs desires, such as in a flirtatious, coquettish or soft manner. This is not allowed whether it is over the telephone or otherwise. Allah has said,
"Be not soft in speech, lest those in whose heart is a disease should be moved with desire" (al-Ahzab 32).
Symptom: Feeling weak?
Prescription: Lower gaze, Do your prayers
Hadith - Sahih Al-Bukhari, Vol. 9, Hadith No. 409
Avoid being alone with a non-mahram except out of necessity and when unavoidable.
Respect yourself and your body; wait until marriage for sex. More importantly, obey your Lord; wait until marriage for sex.
Don't do like the kaffirs, who date. Do as your Lord commands you. Trust that Allah swt knows what is best for you.