He knows a thing or two about bad relationships with exes. But he also was able to reconcile with Lorna, so he has some faith that nothing is impossible. Then when you get time travel involved...

"I can't say I envy you." He doesn't have an easy situation back home, but one short conversation and he's wondering how she manages. "Makes our lives here seem less complicated. The worst we have to deal with is toxic air and undead mermaids."

Funny what counts as lightening the mood.