If you include him in your application and later on chaneg your mind about him, or about your relationship, it will create an issue. If he is qualified to apply for himself, let him do it on his own. Plus, if he is not qualified, you will have to prove your relationship with him by documenting many facts, such as joint lease, joint account, joint something. If you have all of these, then no problem. But if you do not have these, then you might make your case a little difficult. it also depends on which country you are applying from, In India or the Middle East, De facto relationships are not common and might be viewed with some suspicion.