Worried about adult son's relationship

How do you stop worrying about your children? My 30 year old son is in a relatively new relationship with a really nice girl who I've met (accidentaly) on a couple of occasions.
She was with someone else when they met but they both fell hook, line and sinker for each other and she ended it to be with him. I have never seen him so happy and was so pleased to think he might settle down with her after being on his own for a couple of years. They both have pressures at the moment (work, money, studying etc) and she is quite a highly strung person. this weekend, after avoiding him all weekshe told him that she feels pressured and "needs some space". He is devasted as she had led him to believe the was "the one" but now he thinks she wants to end it.

Yeterday I spent time trying to reassure him that he would cope whatever the outcome but when I came home later on, I felt drained and full of anxiety - as if it was my relationship about to end! What is the matter with me? I seem to be unable to cope with problems these days? I think in my quest to see him happy and settled, it has almost become an obsession! I just feel so disappointed it may not work out for him.

This morning I am giving myself a good 'talking-to' as I don't think my reaction is healthy! Worrying is one thing, getting all worked up about something that happens to millions of people every day is another thing completely. I will blame the hormones (or lack of them) as although i admit to being a bit of a worrier, I'm sure I'm getting worse!