I'm gonna assume you mean marrying someone from a different country and culture; "foreigner" sounds very wrong. And since you mentioned pork I'm gonna assume this is about someone from a different religion (say a Christian).

I'm not married myself but I'd say generally you should set boundaries while keeping an open mind. If you have an issue with e.g. Christmas then don't partake in it, but you can (and ought to) let them celebrate it. If you're fine with it try to celebrate with them and see if you like it. With pork, I'd talk with them that I do not eat pork and the result really depends on what would work for both of us. That could be either just not eating pork, or if they are really used to having pork in their diet we'd find an alternative (like two diff dishes), depending on who cooks.
Imo that's the least troublesome way to go about it and it shouldn't be hard to say no to things like that, especially with someone you're married to