Unfortunately, I don't think it is possible to befriend a succubus. As mentioned by Zion, there have been cases in the past where succubi have been befriended or even made into a spouse, but their base instinctual drive to drain humans and ascend their clan hierarchy overwhelms any rational thinking. So from there, if a man were to marry a succubus and she is able to suppress her instincts in the short term, this wouldn't work out in the long term, and their first session of lovey-dovey sex will soon turn into a one-sided drain that will leave the man a corpse and the succubus hungry for more.
P.S. If what I said was wrong anyone please correct me, don't wanna screw up Zion's lore by explaining the wrong stuff XD