By boyfriend I mean a serious relationship where you have been seeing each other a fair while, met one another's families etc.
By 'put first' I mean making sure that your needs are met as best as possible, listening to your concerns and trying to accommodate them, loyalty, sticking to most plans made with you even if other plans come up or you are invited to something else at a later date. Putting your relationship above selfish desires, friendships etc. Obviously it's a 50/50 situation and you would expect to give the same treatment back that you receive.