Generally speaking if one person changes in a relationship/marriage and they do not breakup/divorce it means the other person has also changed in their expectations in order to "go along" with things as they are.
The first thing she needs to do is (softly) acknowledge to her mate that things aren't the same anymore. This may happen while they're eating dinner or are in bed just before turning out the lights to sleep.
Instead of pointing the finger at him, she should say something along the lines of "We seemed to have stopped doing .....and we don't do....anymore.....I miss how you used to.... and I would......etc; I don't want our marriage to end up like one of those.....etc" And then ask him the following questions: "Are you still in love with me?" If he answers (yes), She should tell him that she is still in love with him. (pause) and then ask him: "Is there something you need from me that I'm not giving you?" and then follow up with "Do you have any ideas on how we can recapture what we had?" and add on the following statement: "I really miss the way we used to be with one another."
This approach removes the "blame game" element and gives him the opportunity contribute as a "problem solver". If she does not come off as complaining then he won't become "defensive".
When people are "in love" they want each other to be happy.
If someone believes you are worth the effort they will make the effort.
On the other hand if he shuts her down, changes the conversation, offers her (excuses) instead of trying to come up with (solutions) it could be a sign that his feelings for her have changed and he has no interest in rekindling romance. She has to decide if she can stay in a marriage like this or if she'd be happier in the end by moving on.
There are only two ways to experience joy and peace of mind in relationships: we either get what we want or we learn to be happy with what we have. There is always someone who (wants) what we want. It's up to us to decide if it is worth seeking them out.