As you can tell... i havent caps locked my title like i normally do. but i need help.

I have a friend who's come to me for advice and i dont know what to say.

She said to me that one of her closeset friends has stopped hanging out with her, it takes her like 1 day - 3 days to reply to one message and she said that she feels like her friend is ignoring her.

Thing is she just guess her friend was busy revising for our exam ( we all live in England so we have the same exam dates) but this has been happening for about 4 or five months on the regular now.  Our exams started last month.

she's recently reached out to this friend and asked if they would like to hang out during the time off that we get, and her friends reply was "Yeah sure, but maybe after the exam." My friend knows that her friend has a boyfriend and other friends to hang out with, but this friend has been a major part of her life and soon we'll all be in sixth form ( per college/uni). She doesnt want to stop being this girls friend. The two of us bonded over our (not serious) depression, but that friend is a HUGE part of her support sytem and if she lost them, in her words, "It would be like remving a limb and beating me with it."

I'm usually the one She comes to when she needs advice but what do i say?

should she stop being this person's friend overall, or just blindly keep the one sided friendship going?

honestly it scares me too because these two have been friends for 5 years, nearly six. i'd hate to see them go their seprate ways. And yes, i do have my friend's permission to ask you guys. she knows i come on here for advice.

please help me.