How does Portia that she is more fond of Bassanio than the other two suitors?

Portia shows she is more fond of Bassanio than the other two suitors when she advises him to wait a day or two before making his choice of the three caskets. She says this because she wants him to choose the right one and become her spouse. As she puts it:

in choosing wrong, / I lose your company.

She doesn't say anything like this to the other two suitors, both of whom she endures rather than encourages. When they are gone, she refers to them both as "deliberate fools."
Portia shows positive emotion, however, when Bassanio picks the right casket. In her overflowing love, she wants to give him even more than the wealth she has to offer, which is considerable. She willingly gives him all that is hers, including her ring. She also gets actively involved in helping him save his friend Antonio.