I'm also mature (74), newly in love (she's 72) and feel so good etc. It's normal to feel that good when you're newly in love, and over time (like 6months to 6 years) we usually discover that our great relationship isn't as great as it seemed to be at first. But you don't need an expert to tell you you're in love. In my experience (I was in a realistic/difficult/valuable/sometimes-happy marriage for over 30 years until last Labor Day when my wife died) perhaps the most surprising aspect of some new relationships -- and the aspect that can make you scared you're crazy to feel this way -- is what happens to you when all the negative signals that crop up in most relationships at around 4-6 months (or 9-12 months) just DON'T show up: Because there are significant features of your new couple interaction that are SO different from what has ever happened in your coupling before that it's "too good to be true." Too good, because your unconscious mind (probably cerebellum, where your relationship patterns are kept for duplication when you don't have time or conscious awareness to make quick decisions about how to respond or act in newButFairlyFamiliar situations) kicks in to cope with a less-than-pleasant interaction, BUT it doesn't happen and something pleasant and easy happens instead.
You ARE in fact "crazy" only because what you're experiencing and doing doesn't fit with your well oiled automatic programs for how to act, yet your life is proceeding swimmingly ANYWAY. Pretty amazing isn't it? Endlessly surprising. It could be either because you've lucked into a partnership in which your unconscious patterns just happen to work out great (which astrological charting could show--but who needs it?); OR because you're mature from learning by hard-earned experience how to manage so many of the usual ruts and pitfalls in relationships that what would have wrecked your progress 10 or 20 years ago now glides by without a bump or a grinding of gears.
There is also the matter of how much love and passionate energy you're generating between each other, like the charge developed by a two-person battery. That power can flatten many obstacles that might otherwise interfere with bliss. Sex, longing, and increasingly intimate acquaintanceship with each other's bodies, minds, emotions, histories and spiritual cravings all help build the energy that makes love a triumphant force for good on our planet.
If you want more commentary and discussion, please respond. Or I'll let you rate me and get back to your corner of Paradise without further ado. Your question comes at a very convenient time for me, because I'm living the same high wave as you are; and my new partner and I just keep laughing about how lucky we are, or Do we deserve this? Or how can we broadcast our happiness so that others can partake of it too--and how can we teach others to have such a good time with love as we're having (we're both semiretired professors)