The problem is that 3 months is not long enough to develop real feelings. Sure we think we may love a person the first time we see them, but usually it is more of a feeling of awe or lust. Then another concern is that you develop a habit where you are with a person and even if they are great at 3 months you get bored because you set a threshold at 3 months. You will probably get an antsy feeling and may even feel trapped even if you really love the person, because we can become addicted to that feeling we get when we fall for them and there comes a point in all relationships where the love felt is not the same love felt at the beginning. No offense but it is also as if you are objectifying the people like they are your toys for 3 months and once you are bored with them you just throw them away and find a new toy that is fun again because no legitimate feelings can develop lie that if you know at the beginning that you will let them go after 3 months. It would be hard to make a lasting friendship in three months let alone a loving relationship. If there is not chemistry I get that, but if there is why set a limit of time before hand?