He says he likes 'getting attention as a girl', however, you're a girl, a young woman, do you get showered in attention and compliments wherever you go? I for sure don't.

Something unfortunate to mention here is that while men aren't showered in attention, nor are women, trans-identified men and women very often are. By media, by online communities, by IRL communities, in universities... Being showered in praise and attention by doing nothing but say "I'm trans" and doing a few superficial lifestyle changes must be very tempting to people who feel like they lack that praise and attention elsewhere in life.

Edit: OP, if you decide to keep working on the relationship, perhaps it's a worth a try to see if his urges might be due to him feeling a lack of positive feelings about himself in general. If he had something else through which to gain a sense of confidence and pride, he might not feel the need to get those emotions from crossdressing/identifying as trans. This could be anything constructive, like learning an instrument, helping out in local charities, doing garden-work or anything of that sort.