For this to work, Tessa has to keep up with his ambition. He owes the Navy for his education, so will stay in as long as is necessary. He wants to do an orthopedic residency, be a world class triathlete and do charity work. Oh, and be an astronaut when he grows up. When will he have the time to develop a relationship that brings with it the responsiblity of family?
And my secret, secret thought is that he wants a political wife. I wouldn't be surprised if the political hacks aren't already calling him. With her sophistication and political roots, Tessa fits that five to ten year goal much better than Bevin ever would. So, if Tessa has the energy to nurture him toward his true hopes and dreams, she may make the commitment to continue past the early stages with him. It really is all up to her.