At what point would you say Alex "snapped"?
In my person opinion, Dan had seen multiple red flags around Alex during their little courtship weekend before he began to get sick of her and attempted to avoid her.
1. The way Alex treated Dan's fat, tubby friend. He was just kidding with her!
2. Alex seeming to ALWAYS be there around Dan. Example: Dan coming out of the office during that rainstorm and Alex saving him with her umbrella.
3. Dan trying to leave Saturday night (asking for a cab) and Alex answered him by shoving him into the damn elevator and giving him a BJ.
4. Alex calling Dan Sunday morning after he called his wife. Who knows how many times Alex tried to get through to Dan during that call. I don't think they had call waiting yet, as I think call waiting came out in about 1988/1989.
5. Alex being very demanding about seeing Dan on said Sunday.
6. Alex joking about her dad's death (which really happened, as Dan and the audience later finds out) and Alex fvckin lying about it.
7. Alex trying to make their relationship finite by trying to (subtly) manipulate Dan into forming a relationship with her.
8. Alex starting an argument because Dan was about to leave.
That's not counting that Alex blatantly tried to get Dan to stay with her by feigning a suicide attempt. I understand where Alex was coming from: she wanted a serious relationship with someone. Her biological clock was running out, her youth waning. I believe she was 36 or something (I have to watch it again).
Alex just went about it the wrong fvckin way.
She showed Dan the world on that Saturday night: they had dinner, they had sex, coffee, they went out dancing, and Alex showed off that she can be fun (Elevator BJ, Central Park) but classy (the dinner and cooking for him). She also showed Dan that she was desirable ("I stood him up. That was the phone call I made.").
Dan also had something to prove. He even exclaimed "Thank God!" after Alex confirmed that he was a great roll in the hay.
While neither party is blameless, I will say that it was Dan's actions moreso than Alex's illness that pushed her over the edge into insanity.
Dan avoided her like the plague. That was a serious blow to her ego, as she loved Dan. Dan also rebuffed her numerous times and was quite rude and condescending to her starting with the subway sequence.
Dan also had a knack for completely ignoring and disregarding her. He finally got sick and tired of her to the point where he changed his number, and I don't blame him. I think it was at that point that Alex snapped. After all, changing your number in the 1980s and not telling you was the equivalent of "blocking" you on FB today.
Following Dan changing his number, Alex seemed to get more bold and she committed to stalking Dan full time. Shortly after finding out he changed his number, she just shows up at his apartment. I bet you she pounded on the door until Dan's wife answered:
Alex: "Well, where the fu---Hi!"
Beth: "Hello...are you here to see the apartment?"
A: "Yes! Yes. I saw it in the paper and it looked wonderful!" [Beth invites Alex in and closes the door. Alex starts scanning the apartment, looking for Dan]
B: "Well, I want you to know that my husband and I have been very happy here!"
A: [bends her neck forward so that her irises are parallel to her brow] When's your husband coming home?"
B: [Looks at her watch] "Oh, in about 15 minutes or so. I'll put on some tea while we look at the apartment!"
A: [Grins] "Great."
What say you?!
Knock it off, Hudson.