
Let’s try looking at this from a defensive point of view. You raise from MP and the BTN 3- bets you for the 3rd time. It can get frustrating over time to play someone who constantly applies pressure to you.
How do we deal with that?
Tight strategy
You generally want to be calling 3-bets in position. If at all possible, avoid doing it OOP. If you’re OOP against a good, aggressive player, the best strategy is to simply fold against his 3-bets and tighten up your opening range. Folding is a neutral EV play; it is not a losing play. Unless you want to get into a variance war with the good player, you can tighten up your opening range and wait for a good hand. If you keep folding to his 3-bets, then he’s going to expect you to fight back and stack off lightly. However, you will fight back, when you have JJ+. Villain is going to level himself into calling off with AQs/99-type hands. Just remember that when out of position, it’s a smaller mistake to call 3-bets too tight than too loose.
Playing Fit-Or-Fold
If you want to call with marginal hands, then you have to “play poker” on the flop. You can’t just fold to a c-bet if you miss. Say you have 77. It’s a decent hand pre-flop, but it would be a mistake to call a 3-bet and fold when you don’t hit your set every time. You will not flop it nearly often enough to make it a profitable call pre-flop. Even when you do, you’ll still have to try to stack him off (which is easier said than done since his range is wide and he won’t have a strong enough hand post-flop to stack off). You must be willing to float and make plays if you want to play those pairs and suited connectors profitably.
Let me demonstrate.

You should highly consider betting the river since he doesn’t have a strong hand very often. The board on the turn is drawy enough that he would bet any hand that is better than QJ. As for your range, you can reasonably have a flush. If he had a flush, then he would’ve bet the river. You can also have a pair of queens that went for pot control on the turn and is now betting for thin value. You could also rep a rivered two pair. He might end up calling with AQ+ but that’s rarely going to happen. Once he checks the river on this board, he’s going to check-fold most of the time. And since we can beat ace-high, we should bet.
Calling 3-bets with Pocket Pairs
Even with position, you should fold pocket pairs worse than 99 when stacks are less than 150BB. However, if you know your opponent well and know that he’s straightforward enough to c-bet on a J52r and give up on the turn and river, you can call 3-bets with 55+. If you are out of position, unless the opponent is really passive, you should fold these pocket pairs out of position to 3-bets.