You haven't given us much to go on here regarding your actual story, so let's take this set-up:
MC: Manipulation/Conceiving an idea --> The MC is Pretending to be an inventor in a company and must generate ideas.
IC: Activity--> She is an avid quilter who spends a lot of time studying the Old Masters.
They are going to run into conflicts here based on this. For instance: The MC is forced to create things that are way out there (so nobody can understand them) and relies on "emperor's new clothes" as a strategy: everyone is afraid to say that his ideas are terrible, since he is this "great inventor". Meanwhile, when he comes home at night, he sees his girlfriend's quilts getting progressively better and more impressive since she's taking the slow, knowable road. He is frustrated knowing that his bubble is one day going to pop, and he's going to have nothing to show for it.
They can have all sorts of arguments about this, but are those arguments reflected in the relationship throughline?
Well, no, not yet. Currently, they are just the IC's affect on the MC.
The RS, of course, is that they are both "flesh-eating zombies". (I literally just spun the Brainstorming button for this whole thing.) And nothing that we've said affects the problems they have with being zombies. On one hand, the concern is "being ready to go with something" -- and you could see this being "Are you ready to go with your new idea? I'm ready with my quilt." vs "Your quilt is boring (act one) so I can hardly see how you call yourself ready, when my idea is dazzling and I will be the hit of the party." OR "Your quilt is amazing so I can hardly see how you could even consider that I am ready when my ideas are paper thin and would crumble under the kind of scrutiny you get."
These ideas are very close to the MC/IC throughlines.
But what about: They are zombies and need to be ready to go with a serum that will restore their life and humanity? Then the arguments are going to come from that. When the serum isn't ready, they argue. When it is ready, they celebrate and get nervous that it's all a pipe dream that won't work.
This idea is far from the MC/IC stuff.
Although, to bring it all together, you are probably going to want to blur the lines by having all of the serum work they are doing happen in the lab where the MC has a job (it's why he pretended to be a great inventor) and, you know, she was earning all the money with her quilting to buy stuff to make the serum. So in act one, maybe the issues of "being ready to go" are related to "ready for your job interview?" and "you don't make quilts fast enough" but by the end they are more serum related.
Interestingly, the RS Catalyst I got was "doing a job for something" -- his job brings them closer together because it is their way forward and the RS Inhibitor was "Being doubtful" -- her early quilts are a problem for them because they both doubt they can earn money with them. I hadn't looked at them before I wrote this paragraph, but they fit almost too perfectly.
Can you see how the doubt about the quality of the quilts is both about the quilts and puts a damper on the relationship, which so badly needs the money she can earn with her work (but not yet)?