Loving another always involves some risk. Risk of rejection, risk of ridicule, risk of losing that love you hold so dear. We all want love, but most of us are hesitant to commit ourselves due to such fears.
Those who have loved and lost, feel the pain most acutely. Over time, the pain subsides and one can get back to life again. The next time an opportunity to love comes around, that person is likely to be more hesitant to get involved. This is precisely your predicament.
You've noticed that after two years you feel more able to open yourself again. While your boyfriend hasn't had enough time and mental distance yet to be so open.
I think you two can come together and learn to love again. It will require a positive attitude, perhaps one where you are aware of the mistakes that you made in your last marriages, and strive to make this relationship even better.
But that kind of thing can bring too much pressure into this relationship at this point. In fact that is the basic problem here. The pressure of having failed once, and the likelyhood it might happen again. So the solution requires a complete release from expectations.
After 8 months you two should be able to discuss this frankly, and agree upon a new basis for your relationship where there are no expectations. It's precisely these kind of expectations that doom many relationships and marriages. After all what is marriage but a codified series of expectations.
Don't let yourselves be tempted to commit to anything, like living together, until you both feel it is right. Remove this kind of pressure, and perhaps you'll both be more free to be yourselves. Certainly you'll be less defensive and more willing to go with the flow of the relationship.
In other words, my advice is to go slow, go with the flow, and don't lay expectations on each other. When the time is right to get to the next phase in your relationship, you'll both know it.
Good luck & good lovin'!
The Old Hippy