I answer some version of this enough that it's worth my addressing separately. It can also come out as “I'm not in her class.” or “Why would she love me?” or “I can't possibly live up to her standard.” or “What could I offer her?” or “What could she possibly see in me?” or, worst of all “I don't love her as much as she loves me.” Feel free to swap the pronouns: I'm sure women have the same hang-ups.
There is something fundamental missing in the foundation of many relationships, and it is our unwillingness to go there that leads to the unnecessary termination of a lot of marriages, and a lot of heart ache.
It's like this.
I was at an event the other night, and ended up spending some time at the bar with a handful of women a few years older than I talking divorce. One was divorced already, another still married, happily I presume, and a third contemplating. She, at least it occurred so to me, was not complete with what was. There was a spark not yet extinguished.