A male significant other that possesses a higher level of maturity than the typical "boyfriend". It is usually a term used by women that have very high standards in a relationship and do not have the patience to tolerate immaturebullshit.
"Is Julie still dating whats-his-face?"
"Nah dude, she upgraded to a Manfriend."
"Wow that is one classy fellow....definitely Manfriend material."
Someone a girl continuously has sex with, but you do not consider yourselves in any sort of relationship. "Friends with benefits," possibly minus the "friends" part. No strings attached, a purely sexual relationship. Pseudo meaning not real, manfriend because girlslike men, not boys.
I'm so drunk, I'm going to call my pseudo manfriend tonight to see if he wants to hang out.
I haven't gotten laid in forever, I miss my pseudo manfriend, the sex was so good.