It seemed that Jean still loved Mike. Anybody else see that?

Yes. I believe she fully intended to re-start their relationship. I'll see if I can find a comment I once made regarding this episode, but the gist of it was that Mike needed to be up front with Jean immediately that he was now seriously involved with Sally.

The longer it took while Jean was in town, the more her hopes grew into a belief that seemed to escalate that she and Mike could get back together.

Jean was downright devastated to learn that Mike & Sally were a serious couple. Yet she handled it without drama or conflict. (Through Cynthia Pepper's effective acting, the deepness of Jean's feelings seemed clear.) I just think that Mike in that episode was practically callous about how Jean would feel, he seemed to be practically leading her on.

This is one of the most interesting episodes of the b & w era and I'm anxious to watch it again. In Mike's defense, maybe his feelings for Jean were preventing him from telling her immediately about Sally. Clearly though he should have detected that Jean still "wanted" him.

I once had a situation as an adult that was a little different in that one of the 2 women involved whom I just met strongly suggested she wanted to start a relationship with me, while the other I had known for years I didn't know if she ever really had romantic interest (very friendly but not responsive to hints). So I had to decide, I chose to continue "courting" the latter to a degree, and it blew up in my face -- so I ended up with neither. Mike at least knew both Sally and Jean had romantic interest, although with Jean maybe he simply misjudged how serious hers still was.

Here we see Jean as played by Cynthia Pepper in the episode;
she has just learned about Sally in a phone call in which Robbie
mentions that Sally is Mike's fiancée. She had no idea that
there was a woman in Mike's life (who came along after Jean
left Bryant Park):

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Cynthia does a fine job of portraying Jean's shock and being
fully and outright devastated to learn that Mike is engaged;
as Steve presciently told Mike, he had better tell Jean about
Sally, or one of the 2 ladies likely would be hurt the longer he
put it off.

As it turned out, Sally knew that Mike was seeing Jean, though
she didn't reveal that to Mike. Once Mike found out she knew,
we had one of those scenes where someone throws stones at
a 2nd story bedroom window -- in this case, Mike throwing them
to get Sally's attention to talk with her.

In the end Jean is highly magnanimous, she creates a fantasy
boyfriend and tells Mike she's getting back to him; Mike never
finds out that the non-existent male is just Jean's way of
graciously leaving the scene without ever revealing to him that
she's devastated and had fully hoped to re-start their romance.

Jean deserved better. She had no idea that she was becoming
part of a love triangle. I find it bothersome that Mike's
insensitivity has no repercussions on him, and as Steve predicted
Jean was clearly hurt.