Even if couples are engaged, we would like to stress that engagement in Islam is simply a promise to marry at a future date. Its sole function and significance is to keep other suitors at bay for the time being. There are virtually no other legal consequences that accrue from engagement. Thus, engagement does not make what was otherwise considered haram (prohibited) as halal (permitted). In the eyes of the Shari`ah, engaged couples are still considered as non-mahram. Failure to take this into account amounts to violating the principles of the Shari`ah.
Sheikh Muhammad Iqbal Nadvi, Imam of Calgary Mosque, Canada, and Former Professor at King Saud University, Saudi Arabia, states the following: “As you have not married yet, then what is allowed is what is termed as qawalan ma`rufan or good and proper conversation. So, what is called proper and decent is acceptable and allowed in Islam.
As far as the expression of emotions and love is concerned, it is not allowed now as it may lead to haram things. On the basis of sadd adh-dhara’i` or blocking the means leading to haram, this is not allowed.
Whether parents are aware of the relationship or not, or whether you have the intention to marry or not does not make any difference here, because first and foremost we are accountable for our actions before Allah Almighty. Love talk can lead to private and intimate conversation where Satan can drag you to physical actions, and as such, this way to evil has to be blocked.