Also if you have two characters, you do not have to have them in the same group. (For example Remy is in a group and my other character Olivia ended up in the second group. FaithsRose's Ash is in one group and her Mercy is in the other) Even if your two characters are closely related, there may always be reasons as to why they'd get separated. 

The two groups will come together eventually, but that does not mean they will always be together. After all, this is an undead outbreak and things will happen to force people to split up. 

Don't worry, we will have some times of "quiet" "safe" times, but believe me they won't last forever. So you'll get some chances to develop character friendships/relationships and all that good stuff.