My love/hate relationship with my current WIP

Does anyone else find that they have a love/hate relationship with their current WIP or is it just me? I didn’t have it with my first novel, but I think that may be because it was a series of short stories, so it was all love and no time for hate. It may be because I am branching out into unfamiliar genre territory as I am writing a thriller for the first time and, maybe, I am just lacking in confidence as it isn’t my go-to writing style. I keep finding that some days I am loving what I am writing and feel good about my chapters but others I get into an absolute slump, feel that my writing is dreadful, and the story is going nowhere. It may because I am being ambitious with this WIP. I am writing much more than I have ever written before, it is a longer narrative and doesn’t quite follow a linear structure in the same sense as my usual writing does…and I guess that’s hard. I loved writing my first few chapters and I have had a couple of climatic moments that have been really interesting to write (delving into a bit of gore and mystery which I haven’t always fully gotten into with my writing for a younger audience). It is just those lulls in between where I am working on character development or orchestrating situations to enable the next key moment to happen that I am finding hard. I wonder if that means I just don’t love my characters or world enough and if so, does that mean it is a project worth abandoning?

 Let me know if you ever feel the same way about your WIPs and if you have any advice for these writing slumps.