Doesn't say i love you

Say you're dating someone, and you tell them you love them, and they say I know, how would you react? They tell you they feel like they love you, they just don't know how to say it (but they say it to everyone including friends). They also say, that they may not say it because they don't want to say it then mess things up. Would you believe them? The main question is could you be with someone who doesn't say I love you and if so, for how long.