I think it could work, despite Claire being incredibly driven and Marten being a floater.
From Claire's side, I suspect she's desperate for something to be stable in her life (look at what happened with her family), something she can rely on to always be there. As long as he's not holding her back... she could be frustrated with his floating through life aimlessly, but I don't think it'd be a dealbreaker.
From Marten's side... he's actually not happy with being a floater, and he wants some sort of direction. However, when someone in his life (in any context, really) is controlling, he's prone to letting them take the lead (Veronica, Faye, and Dora all fit in this pattern, really), and going along with them... Claire may be a better match for him in that regard.
Now, where I see the real problem with them? Claire jumps to conclusions very quickly about infidelity, and is physically destructive towards possessions of an alleged cheater... in a relationship that isn't even hers. Marten not that long ago got out of a relationship like that, although one huge difference is that Claire is actively seeking treatment for her anxieties, whereas Dora only went because Faye threatened her with physical violence if she didn't.