I have that problem to, its because you are rubbing a sencitive area, just like if you have your boyfriend suck or lick it, Its the feeling and how it feels
it's just part of the rush, and honestly when your legs get all weak and tingly it's a sign that you're about to climax and cum!! keep going until the end!!
Blood is rushing to other areas of your body, related to sex. Leaving your legs without as much blood supply.
mine do too. i think you just get a bit tired.
*weak. that had me confused.
