Maybe she could reach if she could pin him down and thrust fast and hard into him, but as it stands she's basically being used by him. Used to pleasure him and be used at the same time. It was pretty damn good, honestly.

...though when she starts to feel him getting deeper and deeper, her breathing grows heavier by the second. Her muscles tense, her body twitching slightly from the deep fucking she's receiving. She glances down to see the shape of his tentacle moving beneath her skin and... lets her head fall back while she moans. He's using her deeper than she's ever been used, and she can feel herself building rather rapidly towards her peak. If she comes while he's buried this deep in her, well... she won't be satisfied with just one time.