Acting aside, I enjoyed the liberation of Pat over Alice. This is an unpopular opinion but I never liked Alice's fragility and I was annoyed at her insistence at called her husband Steven, because it always emphasized to me that Alice loved the ideal of a self-made man like Steve, more than the actual guy who was very flawed.
Pat was pursued by many men. She had a career as a journalist that was a key part of her character. She also was a good friend to Vicky. She was a strong woman, capable of raising a child on her own, and didn't need the constant support of her family to be stable.
The twin was definitely before Bo, because she caused problems in Pat's prior relationship to Paul. I don't exactly the recall the sequence of Bo romances, because I think he was dating Mimi (the former cheerleader for Asa's football team, who later romanced Larry) when he was introduced, and then he began a relationship with Pat. Of course, Bo himself later had a doppelganger when Patrick London reappeared with his face, but that's a whole other story.
I know Pat and Bo were together when his mother was first revealed, because they had a remote in Paris, and I vaguely remember that she was at the month long wedding of Asa and Sam when Olympia made her entrance into Llandview. But, I think Pat was gone before the Ralstons were introduced and Bo started dilly dallying with Becky and Delilah. I think she left to take a jod out of town, but I'm sure someone will correct me if I'm incorrect.