The attraction between you could be very one-way, which is difficult for both of you. Your lover is probably less invested in the relationship than you are, and that could hurt at times. You could start off strong, on equal footing, but soon things start to get skewed between you.
You're much more into the fantasy of a real, long-term relationship, complete with love and attraction, affection and intimacy, trust and communication. You really, really want to create this with this person, but they just won't cooperate! You may even start to feel as if they're much more self-centered than you realized, more interested in themselves than they are in you or in the relationship. If you're normally a bit insecure in a love relationship, needing lots of reassurance and affection to feel secure and comfortable, this relationship could push you even further into pessimism and insecurity. You could become jealous and possessive of your lover's time, not caring that whatever they felt for you in the beginning of the relationship faded fast. Your seeming dependency and insecurity turns them off, and that attraction that was strong in the beginning withers. It doesn't have to stay this way between you, though. If the relationship ends up really meaning something to both of you, it's salvageable through careful, conscious communication. Make sure to reassure your lover of your feelings and your intentions.