Bi polar lover?

I have a strange relationship with a man. 

Epic secks, awkward cuddling, and all we seem to talk about is Lulz and politics and yes of course NAKED WRESTLING. I can't read him and I am usually really good at reading people. I suspect it is because he is bi-polar and/or just bat shit crazy. I am not looking for a relationship, he knows that. I am also seeing someone else and he knows that too. But one minute he is totally fine being the side guy, the next minute he wants deets on who I am sleeping with, then he misses me, then he thinks I am a lesbian, then then then then- he is a mother fucking seesaw. But secks is pure awesomeness so I  just deal with the crazy.

Is that something men do? Put up with crazy because the secks is good.

He may be a little perturbed with me as of late. I am a little slower returning phone calls, text messages, and emails and have given him one excuse after another why we can't get together on such and such date. I am not trying to diss, but trying to distance. Honestly, I like him lots- but he is so not stable and so not good for me. I can't shake him though- he showers me with lulz all day long.