My mom is convinced there is something going on between them. I doubt that. I just don't like that my H likes her more than me. It sounds very childish. But I can't help being a bit jealous. I can see why my H would have been irate about OM1. At the time I liked him more than I liked my H.
It's very easy to fall into this trap. Life is hard. M is hard. The first 6 months of any relationship is awesome! There's no serious crap to deal with...there's no bills, there's no kids, there's no tension, there's none of the hard stuff. And frankly, even when there is hard stuff, we gloss over it and see all the positives. That's why you can wait out affairs. Once the honeymoon is over and reality sets in, we all seem like much better options.
I don't think your H likes her more than you....but he can talk to her without thinking of the pain and the choices to come, without trying to figure out what he's going to do tomorrow.
I've read it so many times so I'll say it here for your benefit....make yourself the better choice. This is where being fun, lighthearted, and flirty can really help. It doesn't have to be so serious all the time. I don't say this flippantly....it's extremely hard for me to be that way....but it is so rewarding (and fun!).