Both Lois and Clark's behaviour in these last two chapters seemed out-of-character for me.
The way that you've written him, being sulky, immature, and often selfish, your Clark would have jumped at getting out of the marriage. Up until recently, he had such resentment towards Lois that when Lois said he could get out of the marriage, and she would help him set things straight with Lois, I feel that your Clark would have jumped at it. Him not doing that seemed to be a leap that I think needed further character development.
The big question is why is he staying in the marriage? I think his reason is that he must protect Lois and Christopher. Yet, even in his conversations with Lois, he still has the five year countdown going on his head. It doesn't make sense to me why Clark would want to be Lois' friend again instead of trying to get Lana back.
From Lois' perspective, she knows Clark is still on his five-year countdown. Since she's admitted she's in love with him, why is she settling for friendship? She knows her heart's going to broken in five-years when Clark leaves, so why is she letting herself remain this vulnerable?
They're even talking about Lana getting back together with Clark after the 5-year mark. It seems so odd to me to have a wife and husband talk about the husband getting back together with his ex-girlfriend after the marriage is over. Marriage shouldn't have end dates, so Lois and Clark certainly have to work on building a solid foundation before having any type of meaningful relationship.
I'm eager to see how you develop this forced relationship into something meaningful and potentially long-lasting.
grinch