Well, when you're alone with a sister, and your intentions are not pure then you know the third party is the shaytaan right?

Allaah's hikmah is far beyond ours, so therefore he knows that when we say, ''Oh it's just one look, one time'' you know it's not only one look or time that you're gonna do it. What if someone is really attractive? Then you wanna act upon that look, approach them, and then all of a sudden you can be lead into the haraam, dating.

If you see a sister, who's mashaa Allaah on top of everything -- her studies, household stuff, and taking care of her family and you decide that you want to know more about her then there are other pathways to do so. You can find her brother, or a brother that knows her and ask some questions you'd like to know.

Falling in love is not haraam in Islaam, the Prophet (SAWS) loved his wives very much and celibacy is even forbidden in Islaam. The Prophet (SAWS) used to encourage those who can get married, to do so because it leaves you away the from haraam. We as Muslims believe that love comes after marriage, that when Allaah brings two people together, he puts love in their hearts - in the most halal way possible.

Hope that clarifies things inshaa Allaah.