I have a coworker that has been dating a guy for 5 years and currently lives with him.  His title, “manfriend”.  I use this word quite a bit.  Yenta finds it amusing.  I told her it was a convenient term to use, it’s also more PC than saying “dude I’m sleeping with”.  Besides, the last person to hold the title of “boyfriend” soiled it for future use.

According to the Urban Dictionary

Manfriend
-someone who you hook-up or have sex with but specifically are not dating.

-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 immature bullshit.