Perhaps his girlfriend and him felt it was a group effort, and it had sentimental value to have that in the title.

When my girlfriend and I pursue things intellectually, we feel sentimental about it to some extent.

I can sympathize with OP for choosing the risk of uncharitable readings

It's also largely possible OP did not anticipate the risk of uncharitable readings, and it was not an informed decision

I can understand both an uninformed and informed decision on the part of OP

Edit: clarify, shorten, extend, extend, done ~