She's "selling herself" (must you phrase it like that?) in the way HE felt was lacking due to Genocide telling him she didn't love him. Tom was worried she was just using him for breeding stock and had no feeling for him. She counters with, yes I wanted a child and I really like you. That's all she was trying to clarify, not if you have me I'll make babies with you.
He loved her already, he's said so several times (once while in the lasso and once to her mother), and he loves her as Wonder Woman, as a strong super woman. But the problem came with, again, her maybe using him and not caring a bit about him. This splash page was a DIRECT REBUTTAL to those fears, no need to put in things that weren't a problem.