I agree with the "take it slow" advice.
If possible, dip their feet in the water by dating someone else while you're still "just dating" them, before it becomes a serious relationship and you get too attached. That would give you the chance to see how they actually deal with it when it's more than theoretical.
Gralson: my husband (works out of town).
Auto: my girlfriend (lives with her husband Zoffee).
The most dangerous phrase in the English language is "we've always done it this way."