<human>: We have been seeing each other for about 18 months but dating exclusively for about 10 months. We are slowly moving forwards (meeting each other's family, talking about getting a place together within next couple of years).  The point is, we are getting serious but not married yet, however the understanding was we are exclusive.

He seems to have a very different understanding of "cheating".  To him, if there isn't flesh-on-flesh contact, it really doesn't matter.  I've told him a few times I do  not agree, and I explained very clearly what cheating is to me.

Due to the fact we spend every day together and we often work side-by-side (and sometimes I use his laptop and vice-versa), I have noticed things that bother me. The worst was that a woman he knows on Facebook (she lives 3 hours away) has sent him sexy nude pics for several years now, even though she's in a relationship.  She has continued this even after he and I have been together....bum shots, breast shots, etc. He replies by telling her how good she looks and he'd love to be ______ her, etc.

I freaked out over this and he said he didn't tell her to stop previously because he didn't want to embarass her.  But now he did tell her he's in a relationship and asked her to stop for my sake. She apologized and agreed to, and he said he "unfollowed" her posts but remained friends. Am I way out of line here by thinking he should unfriend her completely? He said he won't do that because it's not her fault.......she didn't know he was with me.

Can you summarize the given text in a few sentences?
<bot>: BF does not feel he should unfriend a woman who has sent him numerous nudes on FB and instead says asking her to stop is enough.