Obstacles stand in the way of understanding each other. You have your own set of values and beliefs, which could be incomprehensible to your lover. The ways that you each think and communicate are alien to the other; you feel as if you have no common ground on which to meet, as if you've never encountered someone who thinks the way this person does.
That's not a bad thing in itself, either, but it's natural to treat unfamiliarity as a threat to the status quo. Your natural response is to cling even more tightly to your own beliefs, even to the point of becoming unreasonably dogmatic about them, unless you try hard not to do this. You both have to work hard if you want to make this relationship work well; this aspect can make any other troublesome influences between you that much more difficult to deal with. The most minor differences in the ways that you think or view the world get in the way of your communication, so compromise is needed. You have to adjust your minds to see the other's point of view if you want to find any common ground at all. The good news is, this shouldn't be terribly difficult, unless there are too many other challenging aspects between you to allow understanding and familiarity to take root. But you do have to change your own ideas about the way things are, in order to allow new ideas to coexist along with them.