I wouldn't really consider it an MMO because it doesn't have tons of players in one game, just up to 10. I don't even know of these terms are subjective or if there's a pre-defined set of rules, but I just view it as that xD RPG element for me comes in being the character and using whatever abilities they have to suit your team, however I kind of see what is missing in the
RPG part of it.
My boyfriend is the same way, he plays a lot o_o but 99% of the time I have his attention. He's the one who got me into it. Truthfully I've only been playing Co-op vs AI for experience, and most of the time with him. I don't know if the trolling and nasty attitude is worse on PvP, but I get it sometimes with Co-Op. Not to any great extent though.
I try to keep a positive outlook by either (a) "how am I the noob if you died more times than I did? and (b) commending players for actually playing like a team and making smart kills (not ks-ing, ugh)