Does Talking to the Opposite Gender Break the Fast?
Question

What is the ruling if I correspond with my female friend on the Net during Ramadan, so long as I remain within the limits of respect, and she opens her webcam and I see her?
Praise be to Allah.Protect lineages and honour
One of the essential aims of Islamic Shari`ah is to protect lineages and honour. For that reason, Allah has forbidden zina (illicit sexual relationships) and has forbidden the means that may lead to that, such as a man being alone with a woman who is not his mahram, sinful looking, travelling without a mahram , a woman going out of her house wearing perfume and makeup, and clothed yet naked. 
Another of these means is a man talking with a woman and her speaking softly to him and tempting him and provoking his desire, making him fall into her trap, whether that is when they meet in the street or talk on the phone or correspond in writing etc. 
Allah forbade the wives of His Messenger (peace and blessings of Allah be upon him) – who were pure women – to display themselves like that of the times of ignorance (Jahiliyyah) or to speak in soft tones lest those in whose hearts was a disease be moved with desire, and He commanded them to speak in an honourable manner. Allah said (interpretation of the meaning): 
“O wives of the Prophet! You are not like any other women. If you keep your duty (to Allah), then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner.” [Al-Ahzab 33:32]
Conversations and correspondence between men and women
Conversations and correspondence between men and women on the internet are one of the means of fitnah (temptation) and evil. That is because these conversations could go too far, which in turn often leads to love and infatuation. Hence we must be strict about these matters and keep away from them, seeking the pleasure of Allah and hoping to avoid His punishment. 
How often have these conversations led people into evil, and made them fall in love and led some of them to something that is even worse than that. 
Shaykh Ibn Jibrin was asked: What is the ruling on correspondence between young men and women, knowing that this correspondence is free of any immoral content or love? 
He replied: 
“It is not permissible for anyone to correspond with a woman who is not his mahram, because of the fitnah involved in that. The correspondent may think that there is no fitnah, but the Shaytan will keep on at him until he makes him fall in love with her and her with him. The Prophet (peace and blessings of Allah be upon him) ordered the one who hears of the Dajjal to flee far away from him, and he said that a man may come to him as a believer but the Dajjal will keep on at him until he leads him astray. 
Correspondence of young men with young women involves a great deal of fitnah and danger, and it must be avoided, even if the questioner says that there is no love or desire involved.”  (Fatawa al-Marah, compiled by Muhammad al-Musnad, p. 96) 
Does talking to the opposite gender break fast?
The fasting person is enjoined to fear Allah and to do what He has commanded, and to avoid what He has forbidden. 
The purpose of fasting is not simply to refrain from eating and drinking, rather the purpose is to attain taqwa or piety – “that you may become Al-Muttaqun (the pious” [al-Baqarah 2:183] – and to discipline oneself, and to give up bad deeds. Hence the Prophet (peace and blessings of Allah be upon him) said: “Fasting is not just giving up food and drink, rather fasting is giving up idle and obscene speech.” (Narrated by al-Hakim; classed as sahih by al-Albani in Sahih al-Jami’, 5376)
In the answer to question no. 50063 we have explained the effect that sin has on the fast, and that it may take away the reward altogether. 
For more, please see these answers: 37654 , 38153 and 36648 .
And Allah knows best.