having difficulty to have sex.

Hello,

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It is quite common for new couples to exhibit problems in erection and penetration.The root cause behind this is performance anxiety,stress and fear.
First of all both of you need to relax before going to bed and indulge in lots of foreplay so that both are excited enough.Usually woman take time to get excited so you can ask your partner to finger you before and then penetrate.He can also use any Lidocaine containing gel which is available OTC and can apply 20 minutes before intercourse and also on the vaginal entrance.Just before penetration rub it off.You also need to be relaxed and for better penetration keep a pillow under your hips.Missionary position or woman on top positions you can try.Ask him to use "Start and stop" technique in which he should stroke and then stop so that he can sustain for long.
Have healthy diet and avoid smoking,alcohol and any stress before going to bed.

Hope this helps