Ive been having an issue where the slaves get into an argument so often with other slaves at the end of the day that all my slaves are instantly fully stressed out.  It's such a huge hassle to fix their stress only to fully have it be maxed out the next day.  Is there any way to decrease how often this happens?

They get closer to each other if they live in the communal room together, and I believe they also do so when working the same job. As they become closer they stop having problems as often. Other than that, I don't know much about this topic.

First, it is important to know exactly which slaves have problems with each other. In the mansion's slave tab you can select a slave and press Statistics to see that slave's relationship status with other slaves. Note, relationships seems to be symmetric (though some parts of the code act as though they aren't), the relationship score going both ways are set equal to each other.

Second, relationships can progress on their own at the end of the day. Very good or very bad relationships are slowly softened towards neutral over time. Slaves with the same job(including rest) tend to amplify relationships, positive relationships tend to get better and negative relationships tend to get worse.(Random chance influenced by relationship.) Though there is a slight chance bias towards improvement, there is a smaller, silent effect that always amplifies the relationship. Thus I don't recommend this method for conflict resolution.

Sleeping together only improves relationships by sharing your bed if they like each other or both have the Fickle trait. The headgirl is guaranteed to slightly improve her relationships with all slaves in the mansion. The farm manager has a moderate change to relationships with slaves in the farm, which depends on those slaves' having obedience >= 75.

Third, the best way to improve relationships between slaves is to have them both join you for sex. So long as both consent to have sex with you and they don't use punishing actions on non-masochists, all actions started or ongoing between them will improve the relationship. There is also a moderate bonus to the relationship if one of them gives the other an orgasm. By maxing the number of ongoing actions it is possible to max out a relationship with 2 to 3 sessions. You can check the wiki for how to get trained traits to improve sex slightly, but they are entirely optional.