I'm very sorry for what's going on with you. Here's hugs and healing from one lonely person to another!

I can really sympathize with your situation. I isolated myself from my friends when I was with my ex because I was outgrowing them anyway and he and his friends were better friends to me than they were. Now that we're broken up, I don't have any friends here in person (all the true ones have moved off somewhere).

One thing that might help you with your fiance is to insist on going out with him. Couples do things together. Not necessarily ALL the time, but he should take the time to be around you in public in a social setting. It's fun to go out with your partner to a bar (even though most people think it's for singles to do). You can make some friends and hang out with him in the same process.

Also, I feel that if you do this, you will know what his intentions are, in the process. It's not always wise to test people, but sometimes it's better to know the truth -- especially when you're supposed to spend the rest of your life with him! If he is happy about you wanting to go out with him to the bars/pubs, then all he wanted to do was just have some fun outside the home and he's probably very happy that you want to go along with him.

I know it sounds pessimistic, but his friends can be your best friends or your worst enemies. They could be encouraging him to do stuff that he normally wouldn't do otherwise (everyone has moments of weakness, after all). This could be why he talks to other women. If I were you, I'd just go right to the source (where he's hanging out) and see what the deal is yourself for your peace of mind and so you will feel better about your relationship.

Again, much hugs and healing to you. It's no fun being left out like that (and believe me, I know).