It seems only a small of relationships retain the loved-up, 'truly, madly, deeply' passion for the long-term....
The issue is that the majority of us tend to assume that this is the ideal to which relationships should aspire, and we feel we're failing and the truth of the phrase 'comparison is the thief of joy' becomes apparent.
However, although I'm happy for those people in such long-term 'blissful' relationships, I don't think it's something I actually want...
Whereas being 'in love' is very pleasurable, it is intense and all-consuming, and existing in such a febrile state of obsession permanently with your partner would lead to a loss of perspective and sense of self, and an unhealthy dependency.
The few couples I've seen like this are frankly tiresome to be around, and closed off from developing meaningful relationships with others, with a disproportionate amount of their emotional energies focussed on their partners and 'their bones'.
So 'love' as a deep, abiding feeling of connection and respect, coupled with enough passion, sex and romance to add excitement and fun in an otherwise balanced life, "yes".... But being 'in love' with all the butterflies, intensity and breathless, all-consuming passion that entails, "no, thanks" at least as the settle state of a long-term relationship.