I would think that it being a crossover doesn't help it gain hits. I tend to avoid even looking at crossovers unless the summary makes me really believe that there is a reason I would like to see those characters together. And of course, that is subjective to me. For some reason someone has decided that a Battle Star Galatica charatcer needs to appear in Haven. Honestly, I despise BSG and will probably never click on that fic no matter how much I like Haven. There is a fic that has Tony Stark land in Haven, and I might someday get bored enough to read that one, since Tony really doesn't like magic, and the Troubles tend to ignore the laws of physics. But I haven't read it yet, because I prefer not to think of Haven as being in the same setting as the Marvel movieverse.
So, yeah, crossovers in particular are hard sales. Then there are all those people who click on it, read a paragraph or two and decide this isn't for them, and the people that go back to your story, hit chapter one and then bounce up to the newly posted chapter. It is kind of neat that ffnet tracks the hits on each chapter, but I would expect chapter 1 to always drastically outstrip the rest.
The point about WIP's is very true, also. There is nothing worse than getting into a story, then the author not finishing it. Most of the time, I won't pay much attention to one that isn't finished, unless that author already has a sterling reputation when it comes to story completion.
I hear you on the wishing for more reviews and likes. Those things are addicting! Mine, I know people are still clicking on it. The number of hits keeps creeping up, but I haven't gotten a comment or kudo from the last 150 hits or so. Every time I check my dashboard, I'm like, 'Come oooon, new comment! Darn. Oh well, at least got another hit.' Considering how very tiny the Haven fandom is on AO3, I'm really not sure where this continuing trickle of hits is coming from, really, but I do like seeing them. :D
Still, you really have to write the story because it makes you happy to do so, not because of the accolades it can bring you. Seeing the hits, likes, and reviews is awesome, but if their numbers are going to bother you so much, you may need to take a few deep breaths and refocus on why you started writing this story in the first place. (Unless it was purely to get hits, then ignore that last bit and go write short shipfics of the two most popular characters)