it kind of irks me when people act like there's only one definite reason why house didn't end up returning cameron's affections. because yes, obviously you can have your opinion, but it's kind of ambiguous. so here's a list of potential reasons (that also in part describe their relationship) because I can:
house didn't like her romantically, and as such didn't want to make it a real relationship, but he enjoyed the ego boost so he did encourage it in other ways. (<- kind of short because if I go too far into detail I fear my bias against it may show)
house truly believed that cameron only wanted to fix him (or didn't truly love him for some other reason, which is arguably more likely), and was trying to protect himself, her, or both of them from a dead-end relationship. depending upon how you read it, he may still love her (and. quite frankly. he clearly liked her/was attracted to her at the very least), and he may have eventually recognized that this was not the case. he may have discovered the difference between healing and fixing. it doesn't matter in the end — cameron made it out free, if scathed.
house felt kind of guilty (perhaps 'I won't crush you' if you'd like) because. sure she likes him. but he's too old and too broken for her, and so he either doesn't let himself feel that way or he simply naturally doesn't; so he tries to discourage it. and yet, he still can't bring himself to really reject her — just to disappoint her until she recognizes that he can't be what she needs. maybe, at some point, he realized she didn't care. maybe he was ready for her. but it was too late.
house did not truly believe that cameron only wanted to fix him (or basically forced himself to believe that she did, but he recognized deep down that this was in not the case) but was shielding himself because he either couldn't believe that she would actually love him (<- similar to 2), or he was too frightened of an actual relationship back when she was available and pursuing him. by the time he realizes that this isn't the case, she's already escaped and moved on; in trying to drag her back, he only helps her to solidify her decision: she needs to move on from ppth (whether (up to interpretation) she still loves him or not).
there are absolutely more but this is it for now, just to make my point of it being ambiguous.
