How to explain the phrase "set up" here?

Question

It's from Friends(Season 02, Episode 04): Transcript Here

The episode reveals that Phoebe had married a gay man long before, because he just needed a green card. But one day he came to see Phoebe and invited her to go skating. So Phoebe dressed herself up, which was not necessary because her "husband" is gay. So when Monica saw her wearing such beautiful clothes, she said:

I can't believe you're dressing up for him. I mean, you're just . . . you're setting yourself up all over again.

What's the meaning of set up here?

Answer 1

To set yourself up, in this situation, means that you are doing everything to end up in a certain situation.

The situation in this case is probably (I don't know the episode) where Phoebe has actual expectations of the relationship (she likes the guy) and wants to be more than just friends.

That situation is likely to lead to disappointment, and from what I understand, it is what happened earlier when she married him.

By dressing up for him now, she shows she is having the same expectations again, so she is setting herself up to end up in the same disappointing situation: she wants more from him than he wants to give.

Another way to say it would have been:

You are setting yourself up to be disappointed and hurt all over again.