Bulma you have no idea what The Doctor is capable either and yes because he is lonely.

"You belong in this universe. I don't."

Ten eyes over at Trunks about his father being one of the last two with very deep and personal sympathy and then at Bulma.

Then the sympathy and sadness seem to fade because both of them sound like they have makings of companions, "Sounds like you both have quite the adventures." The Doctor grins.