this website made me worried

Top tier fraternities hang out with top tier sororities. But, keep in mind that there are now something like 12 sororities on this campus now. So, that said, there are around 10 fraternities that have socials and hang out with sororities. Although you may not always hang out with the Kappas, Dg's, and Gphis, you will still have a good time as long as you are in one of the houses that still spends significant time with sororities. If you pledge in and really hate it, then drop. But as long as you're in an okay house, its probably better than being a geed.

what house?

Your decision to drop or join any house should not have anything to do with this website.

you can talk to anyone you want. seriously??

This is America, you can talk to whoever the hell you want. There's no laws governing whether or not you can talk to girls in sororities that you normally wouldnt have socials with.

The reasons for these perspectives on who hangs out with who is just exposure. A girl in Gphi/Kappa/DG is going to be around guys in say DU far more often than she will be around guys in Pike. So obviously, there is a much higher chance that she will befriend, hookup with or date a DU than a Pike. Obviously there are exceptions to this; maybe you are an exception!

That being said, and this is kinda depressing to say, you should probably be prepared for your friendships with girls in houses above you to dwindle a little bit. This is because these girls just aren't gonna come to your partis, you wont have socials with them and they will end up chilling with different guys.