All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Loving someone for the sake of Allaah is one of the strongest bonds of faith as stated by Ibn 'Abbaas . Through it, the slave of Allaah tastes the sweetness of faith. Anas bin Maalik reported that the Prophet said: "There are three qualities whoever has them, will taste the sweetness of Faith: To love Allaah and His Messenger more than anyone else; to love a slave (of Allaah) only for (the sake of) Allaah; and to abhor returning to infidelity after Allaah has saved him from it as he would abhor to be thrown into the fire (of Hell)". [Al-Bukhari and Muslim].
Indeed, the Prophet established the brotherhood bond amongst the Muhajireen (the Muslim emigrants from Makkah) and Ansaar (The Muslim residents of Al-Madeenah). Undoubtedly, women were included in the bond (amongst themselves) as there is no evidence indicating that this was only established amongst the men.
Islam encouraged that a person should inform his fellow Muslim of his love to him, but this is strictly within the same sex. As for men with women, then this falls under the general love of the person towards his/her fellow believers, men and women alike. However, addressing the opposite sex with statements of love could open the door to evil, especially that there is no evidence to substantiate the permissibility of doing it. Doing this on the net (whilst chatting) certainly leads one to follow into the footsteps of Satan, which we were commanded to stay away from; Allaah Say (what means): {O you who have believed, do not follow the footsteps of Satan}[Quran 24:21].
Allaah Knows best.