Many of his peers believed that, had he chosen to, he could have played Quidditch professionally and would have been good enough to play for the English national side. But Charlie Weasley had other plans. He wanted to study dragons and so moved to Romania to do so. This shocked his mother since that line of work was very dangerous, but she eventually accepted it.
What Molly couldn't accept was that her second eldest son seemed to have no interest in getting married. All his siblings have grown up and gotten married and yet Charlie was nearly 35 years old and Molly was getting upset about not having anymore grandchildren running around the Burrow. Even Ron and Hermione had managed to settle down in the 10-12 years after the final battle.
So what's Charlie's problem?
1.) Charlie could be gay (even though Rowling has said he isn't).
2.) He has a crush on a Romanian witch/wizard and just hasn't had the guts to ask her/him out yet.
3.) He's scared to introduce his long time girlfriend/boyfriend to his family (she could be a former Death Eater).
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