I'm generally squicked out by power imbalances in romantic relationships. But I've learned to try to mellow on these things. Good for Barney and for the Commonwealth for making his marriage as legitimate as mine.
Right, but my thoughts are that a 40 year in a relationship with someone much older isn't in a relationship with a power imbalance. How on earth would someone much older prey on someone middle-aged, who likely has assets and an established career? Of course, you can make the argument that Barney Frank has a lot of power due to his position and reputation, but that doesn't have anything to do with age. Unless you're saying that the imbalance is the other way and the 42 year old has power over the 72 year old, due to the fact that he's past his prime. But this is Barney Frank we're talking about, so I doubt that.
Or it's possible they have a lot in common like my father and his wife. That can happen and it can work.