@Kaarme the lore reason is that our Mc’s energy is so great it would kill her, hence mike being a sponge for it as a divine being vs. the great great great etc granddaughter of the succ queen
@Kaarme from what it seems, Nono doesn't know how to deal with the energy. She's a succubus who apparently doesn't understand how to control her abilities or energy at all, and in turn doesn't know how to deal with the immense energy that Yuuki puts off when he gets excited. So because of that, Mike has been consuming the energy all this time so that Yuuki won't basically self-destruct from the energy. Up to this point, Mike was able to do so, but with Nono it seems like it got exponentially more difficult because Nono is also subconsciously emitting incredible succubus power with Yuuki, and Yuuki is outputting incredible amount of sexual(?) energy as well. So seemingly Mike is barely being able to handle all of it at the moment. Perhaps when Nono becomes more capable of utilizing and controlling her powers, she'll become the perfect partner for Yuuki.
@Kaarme on the one hand, Mike might actually be unnecessary and just doesn't want to be not a part of the family in spite of the struggle. On the other hand, MC's libido is so stupidly potent that it can bonerlessly overpower a normal succubus at a dozen paces and even break magic. It's not clear how it affects normal people, but based on previous chapters I think it's hazardous otherwise I don't see a reason for anyone else to be informed of his condition.
@Kaarme Yes, Dude. the wingman path. To embrace many block sugar and precious particles aren't an easy feat. One needs to steel his heart or he can't withstand the wave in the long run.
I believe Mike is there to keep the MC's Big Dick Energy from spreading and affecting others. As you saw in the beach chapter, she put up a barrier not let people in but to keep the libido from going out. Honestly, I am curious how far a radius his big PP power can radiate, especially if Nono's acting like some sort of amplifier to his miasma-like frustration.