This is one of the calmer combinations in the model, and the reason is easy to miss. The two of them barely differ on the measures that produce heat: neither ignites quickly, both come back to normal fast, and both have a similar tolerance for noise and interruption. Households like that are quiet, and quarrels in them are short.
The friction sits somewhere else entirely, in how a week is spent. One of them refills among people and treats a full evening as rest; the other refills alone and treats the same evening as work. Neither is being difficult. Left unnamed, this turns into two people who each think they are the one making all the concessions.