Honestly, as a parent myself, I’m on board with your boyfriend. The kids come before anyone I date, and I would do the same thing if my kids weren’t comfortable with someone I’m dating just yet…. but there are things your boyfriend can do besides forcing the kids to be in an uncomfortable situation, especially when they’re worried they’d risk the love of a caregiver.

Most importantly, the mother needs to get over it, and she needs to have a talk with her kids that she will NOT reject them. I would suggest that your boyfriend have a talk with her, help her to see that it’s not good for the kids to be living in fear of their mother rejecting them for any reason, and that it would be better for everyone, mostly the kids, if their mother’s love is unconditional. If they can get that resolved, then the kids should feel much better about being around you, and your boyfriend shouldn’t have an issue with you all being together.  Sometimes talking together with a psychologist/mediator can help a ton with these discussions.  I know that’s what it took for my daughter’s father to finally stop acting like a jerk, and he even apologized!

Otherwise, if he won’t stand up to the mom and make sure they both as parents let their kids know that their love is unconditional and they won’t ever reject them, he’s going to have to not bring anyone over until both kids are grown and moved out, and in that case, you might be wasting your time unless you don’t mind the possibility of things staying the way they are for the next 7 years or so.