The deeper you've gone with this relationship, the more you've felt the influence of this aspect. As it went into effect, you both started to realize that something just wasn't quite clicking between you, on a deeply profound level. If you can acknowledge any issues right away, talk about them and find a way to compromise, things will be much easier for you.
But unless you have strong and positive communication going for you, that's unlikely. Instead, you probably noticed that more and more frequently, you two just weren't seeing eye to eye. This is a threatening feeling for both of you, and arguments may erupt as you each try to convince the other of your own point of view. The problem may be one of independence versus vulnerability -- your lover feels threatened by your sense of independence and individuality -- but it may be a simple problem of boredom. You might just find that you don't excite one another as much as you may have thought. But since you're already be deeply involved, you try your hardest to make that be untrue. A better approach is to communicate about the problems between you, and figure out what adjustments need to be made. If it's simple boredom, you should be able to figure out techniques to spice things up. But if it's more about vulnerability and insecurity, those feelings have to be faced in order to be overcome.