Well, i have friend similar to TS situation, but luckily they are not married yet, still got time to think.

TS really need to sit down, get a formal talk. IF hard, then pay some $$, get a mediator/consultant/lawyer to host the talk. Casual talk/discussion wont help, it will probaly come out with "ok ok ok, we see how then"

Post #2 & Post #3 obviously dont understand the actual situation, how things changes over time. TS emphasized he wan kids, and he is not pet type person, u still ask TS to go along -.-