Speaking of the ladies. Do you think that maybe he has bought them meaningful gifts..
First, Cath has many images of butterflies in her home and office, which no doubt have come from Gil. If he were to give something meaningful to Sofia, esp when she did decide to leave for Boulder City, it would be a one of his prized butterflies and/or a book by his favorite author (Shakespeare or some philosopher). This gives him the accuse to call her and have a handy topic to talk about.
Now, I could very well see Gil taking her to a nice restaurant and not some dumpy diner in Unbearable. Also, he would crank up the charm, get her a rose and suck up big time to keep her from bailing on him. Whatever he did, it worked for awhile as she is the type of woman once her mind is made up, there is no changing it.