Skorp1o, contrary to popular beliefs and opinions, "happiness" is not a feeling or state of mind. As Aristotle famously argues in his Nicomachean Ethics, happiness (eudaimonia) is an activity (energeia). The fulfillment or satisfaction of an activity effectively stops the joyful practice of that activity. Take the practice of fucking, for example. While engaged in the activity of fucking, the fucker is keenly happy. However, when the satisfaction toward which that activity, it being fucking, is achieved, e.g., in orgasm, post-coital tristesse ensues. The "happiness" of this example lies more in the present tense of 'fucking' rather than in the past-tense of having 'fucked.'
Your married friend seems to confirm this sage wisdom. He seemed "happier" while engaged in the activity of getting married, analogous to 'fucking,' rather than in its upshot of being married (analogous to 'fucked'). So you see, that's why he is not happy, but is indeed fucked (QED).