Title text: But the past was much too cramped!
To understand this comic you have to do some back-and-forth reading. Cueball, in the last panel, is telling Megan in the first panel to come explore the future with him. Since the panels appear in chronological order, he is literally in the future. Megan replies that she can't, since she is not drawn in the last panel, a.k.a. the future. She is stuck, and it may be implied that she had passed away before the future came.
Cueball is sad about the past, shown in the title text, because Megan had a relationship with Hairy and not himself.
- [The comic has three panels. In the first panel, Hairy and Megan are holding hands. There is a voice bubble originating from Cueball standing in the third panel.]
- Cueball: Come explore the future with me!
- [And Megan says something which goes to the third panel.]
- [The two voice bubbles cross in the middle of the second panel.]
- [The voice of Megan says…]
- Megan: I can't.