1. he doesn't love her
2. he does love her but is incapable of that kind of intimate caring conversation although physical intimacy comes easy for him
honestly, the phrase is overused and abused. You should tell your friend that it would be better to hear it when it's for sure that it's meant than because of some "obligation". Once it is said once, then there is an obligation to keep saying it. You want to know that first time is true and seriously, I don't know how many times these days that happens.
Every girl wants to hear that, I know I did. Has she said it to him? What was his response? I know that is kind of putting him on the spot, but it's a really good way to see what his reaction is.
I told my now fiance (we've been together 8+ years) that I loved him (this was in the beginning of our relationship) and I got nothing. He ended up telling me that he cared about me a lot, but he didn't want to tell me he loved me unless he knew for sure. At the time I was devastated, but today, I'm glad he did it that way because when he finally did tell me that he loved me, it meant that much more.
I wish your friend the best of luck and I hope she doesn't let this be a deal breaker; at least talk about it first.
They obviously take the words very seriously as sometimes so few people do :( I remember personally steering clear from first dates telling me they "love me" when in fact they didn't know too much about me to start with. Some people are just in love with the idea of being in love and not the person. So consider this a good sign in their relationship that the person is actually taking time to say it. I am sure it will be worth the wait :D