It isn't advisable to keep silent over some one you love because silence is gradual killer of feelings, it is very important to reserve while taken your time to study someone but the moment you love the person it simply means you are convinced beyond available doubt that you are in love with the person, fear of rejection should not keep your love in side, work up to the person and let him or her knows your feelings sincerely, keeping silence can make you loose the person because he or she may not notice your feelings towarda him or her.
However, if you are couples already, it is not advisable to be silent while you watch someone you love treats you badly or go astray and because of your pride or ego you opt to be silent, it will also affects you too emotionally.