I can tell a lot about a person from their eyes, but the way I perceive it is in the form of energy.
Considering only eye contact, nothing is ever clear to me about what a person is thinking or feeling. I only get a good general idea whether their internal state is positive or negative. But that feeling may have nothing to do with me, it could have to do with how content they are with themselves, with the current situation, anything!
So, especially someone I do not know very well, I would never perceive positive internal energy as "Omg I love you." At best, it would indicate that the person is comfortable around me, but that doesn't mean a lot as I can be comfortable and happy with everyone but it doesn't imply romantic interest.
I am the worst at guess-what-I-am-thinking/feeling games. So far the women in my life have had to be fairly straight-forward for me to understand their intentions and desires.