Well, I'm following for the car crash of it all. There's the saying what's for you doesn't go by you, and I think they'll get what they deserve.
They are going to have a difficult time with Teddy after the trauma (enmeshment) they've caused him, and Al will be lucky if Isla wants anything to do with him at all when she's old enough to understand the disgraceful and disgusting way he has behaved, both through the original affair with Jen and the continued attempts to decimate her mother's character since. They've sown the seeds.
I totally agree with what someone has said previously about Jen's anxiety being related to the relationship. Any woman knows, even if they can't admit it to themselves, that you can never trust a man if they started their relationship with you by cheating. He's just going to cheat on you, too. She must be feeling especially insecure considering the fact he is obviously desperate for another child, which she is unable to give him. And, as she is much older than him, is increasingly less likely to give him as time passes.