My two Wyandottes barely met today and the roo is already crazy about her and trying to mount her is

She will lay eggs even if there is no rooster when she becomes old enough, now they will just be fertile. You should probably get at least two more girls for your boy, but many would say you should get lots more.

 

How old is your roo? It's been my experience that Wyandottes are very territorial, possessive, and combative. Toward their humans, that is. They are also quite horny. Get more hens for him or he'll wear this one out.

You also need to carefully establish your dominance over him or else risk not being able to get near those eggs when she does lay them.

Also, he doesn't have to "like" her to want to mount her. It's all hormones, and Wyandottes have no shortage of those.

 

What azygous said is definitely true, in my experience. My Wyandotte rooster would follow me all sneaky-like when I was turned around. He was killed by a fox before he got up the nerve to attack me, though. He was constantly on the hens, and hated my other roosters.