How

Clearly the subject of this song is heartbreak. Claire talks in this song how she's dealing with her current heartbreak, which clearly she isn't doing that well.

"Could this be the end of you and I for now?" Here Claire questions the partner if everything is over, for now.

"Hope that I see you soon" However Claire wants to keep in touch with her partner, and in this phrase Claire means that she will miss the partner no matter what, and that she will always be for them.

"Don't know what to do. My heart is under the weather." Without the partner Claire feels lost. The metaphor 'under the weather' mainly has a bad meaning, which means being sad etc. So after the breakup her heart isn't doing that well, it's clearly broken.

"I know I'm the only one who can heal it." Claire is positive that she will get through this heartbreak by her own, but somehow she finds it very hard and we can see that at the phrase "I try to beat the struggle for you, but that's just too hard for anyone to do"

So long story short, Claire is experiencing this breakup very badly and she is missing the partner a lot and hopes that soon Claire and the partner could be the same way as they used to be before.