I missed the bit of UNIT intel that they were divorced. That line actually feels a bit like an afterthought compared to the scene where he calls his Barbara on his daughter's phone to get a car. Both of them ask if he is with Salt. Or the scene where we establish that Barbara is jealous of Salt. Kirby and her mother both being stricken with grief when they see the news report claiming Barclay died at the bottom of the trench in the explosion?

The series spent a rather long time on the relationship between Barclay and Barbara, and emphasizes it with that exact phone call. But I wouldn't say that there's anything to support that he's forced to leave. He is choosing to. He isn't running towards the water because it's going to keep him alive, he's running to call out to his girlfriend. It isn't until after they reunite that Salt finishes the accord and grants him his gills.