My boyfriend is a liar and I am a bullshit detector. I used to call him on it, especially because most of the things he lies about are stupid. Since I'm married to someone else, I couldn't care less who owns his home, or why he has no veteran's benefits even though I know for sure he spent 8 years in the army for example. But I gave up on that because he would never admit to lying anyway.
Sometimes he lies about things that do matter to me. I can always tell when he is trying to hide that he has had sex with someone else. I can tell he is used to jealousy, and just trying to avoid drama. But it's an open relationship and I am married! I expect him to have sex elsewhere when he wants to. He works in a bar that is a swingers meet market! I also think he lies about women because I told him I would leave him if he was insufficiently discriminating. For example, I trusted a woman and her husband because they are his friends. I didn't ask any questions. I just agreed to a foursome with them because he knew them, and we all wanted to. Later, I find out the wife goes to adult theaters and porn shops with viewing rooms, and sucks as many dicks as she can, and tries never to suck the same dick twice. I have forbidden sex with indiscriminate women, but he loves their adventurous side. I try to remind him that I don't accept every person who wants me, but I have been very open and willing to have new experiences.
When I call him out on this type of lie, of course he can't admit to lying. So I remind him that I encourage him to have other partners, and I just want to hear very honestly about how he met them, who they are as people, what he did with them, and what steps he has taken to protect my husband and I from STDs. After that reminder, he will be honest about it again for a while. Then on day I will know he's hiding someone from me again.
It has never been my habit to tolerate lying. I always say you deserve what you continually get, because you will continually get what you tolerate. I especially do not tolerate lies about sex because that is something I consider dangerous. But for some reason, I never leave him, and I'm not planning to. I have never been so well-fucked in my life. I can't imagine having to give up sex with him forever. I really don't want to. I think he knows. I think he knows he can keep lying and I will keep laying with him. I'm not sure he knows how much truth I do know. Months ago I stopped poking holes in his bullshit and just let his false words stand.