There's no fixed law about that, Mia. Many people would say if you are fond of two people at the same time, one or both may be fondness but wouldn't be love. And part of the problem is voluntary and involves choices --- you don't HAVE to allow yourself to get emotionally involved with 2 people at the same time. There's aspects you can't control in who you find you easily like, but falling in love isn't like being hit by a meteor. totally at random --- it involves voluntary elements, and putting yourself in situations in which it can happen. I don't think that one day you pull up to buy petrol, and suddenly, helplessly, fall deeply in love with the petrol pump attendant.