Sure. He left college after getting his batchelor's degree, so it would be conceivable for them to be the same age, with your character just staying in higher education. Though, her having passing knowledge of 17 languages while also being an accomplished mage and holding a master's degree seems a little far-fetched, especially someone evidently in the top fraction of a percentile of human intelligence going to school with someone who is functionally average. Such accomplishments would certainly color the relationship, at least.

As for knowing each other, it is good with me. Geoffrey is the most /k/ommando character I could come up with, so a little goofy magical nonsense would be a welcome addition.

By the way, I hope you allow a little bending of reality when it comes to Geoffrey acquiring weaponry, japan is a no-fun hellhole and him getting the toys he needs to stand up to what are shaping up to be Mythos-level threats is going to need some suspension of disbelief.