who mixes with who

No one on this website can give you a comprehensive guide to which houses mix with which houses and details about the relationships between houses because (surprise) you would have to be in an organization in order to speak about the relationship between that organization and other houses and no one on this website is in every fraternity and sorority. Also everyone on this website has an agenda.

Houses usually stick within their tiers.

Alpha Phi, DG, Theta only mix with "top tier" houses. Exceptions include APhi being close to Sig Pi and DU and Theta being close with Chi Phi and DX. SDT tends to sacrifice having a full social schedule in order to exclusively mix with upper tier houses (DX, DU, Sig Pi, etc.) and they are very close with ZBT. Kappa mixes with most top houses except for Sig Chi and are close to Alpha Delt and DU. Tridelt is an anomaly in that they mix with pretty much everyone (a weekend with them could include DX, Sig Phi, ZBT, FIJI, etc.). Pi Phi mixes well with middle and upper middle tier fraternities like DX, DU, and Sig Pi.

I'm in a sorority and don't know much about the schedules of houses outside the top and middle tier, so this is all the information I feel confident giving. Just be aware that I, also, don't have a comprehensive guide to all of these sororities' social schedules and realize that regardless of which house you join, I certainly have a ton of male friends in houses my house does not mix with, as do a majority of people.