can the mc still date cove during this?
Yes, you don't have to romance Derek to enjoy his scenes. But Cove almost never appears on screen during Derek's Step 4 story. It's referenced that Cove is your boyfriend if you are dating, though.
almost? are you saying he appears with lines then?
You get to talk to him over the phone in Step 4 and he hangs out with you sometimes in Step 2, haha.