Nagi is really starting to annoy me, i mean i always disliked her, felt she was horrible in comparison to Athena, Hinagiku, Ruka, Maria and the rest but if she did her thing then i just looked over it, but now she is tying down Hayate to not only financial obligation but moral one also, thats not right at all....she is basically ruining his life, sure he may be having "fun" but if one thinks about it, it is because he adapted to a scenario where he had no other choice, it made him view the positives of being with Nagi rather than thinking about the other possibilities he could have had if he weren't her butler like being with Athena for example.
The whole ending up with Ruka is very unlikely, which is unfortunate since in character alone she destroys Nagi, but that said hopefully when all is said in done if Hayate must stay with the useless parasite then hopefully she at least becomes more independent so its not obligation that makes him stay with her.