Hello roxannefrommacungie,
We see that you need help with calls on your iPhone.
First, make sure that the contact isn’t blocked by following the steps here: Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch
If they aren't, see if you can get calls from other contacts. If so, see if your fiancé can make calls to other people. If either of you is having an issue making or receiving calls from other people, contact that person's wireless carrier.
If both of you are able to make and receive calls, check for third-party apps that may be blocking calls. Detect and block spam phone calls.
If they are not blocked and there are no third-party apps, your wireless carrier would be the best point of contact.
Cheers!