Is marriage ever the same after infidelity?

I don't think so because the trust isn't there anymore.

Not really. From everything I read on the topic and everyone I’ve talked to, the marriages that survive infidelity in a lot of ways are starting from scratch with hopefully a better foundation and more effort than the first go. The deciding factor is often whether the two people have a good feelings about their relationship anymore we’re both people believe it is worth saving, whether the cheater is willing to do whatever it takes to redeem themselves, and whether the person who was cheated on can muster compassion for the cheater’s reasons.
Often the cheater feels justified, so there’s only so much they are willing to put up with from the person they hurt or they already weren’t that invested in the marriage anymore, hence the cheating.
Often the person who was cheated on doesn’t consider the cheaters reasons understandable.
Sometimes one person can’t forgive the other or ultimately both people can’t forgive each other.

It’s a very hard for both people to heal from together.

Depends on the reasons why it occurred in the first place

no and rogueloner said it best. Iknow first hand

Some times it can strengthen a marriage.

It certainly doesn't seem so at the time; but some find that forgiveness is possible after A LOT of time and counseling. Enduring that can be excruciating, but it's not impossible. No, things won't be that same as they were, but a new trust and connection can be forged.

I'd say no, but that's just for me.
For me, if someone cheats it's immediate grounds for divorce.

Sounds like you need to have a proper discussion with your other half. Ask them why they felt they needed to cheat on you and what is it that they felt they can’t get from you that they got from the other person?

Was the cheating done for sport?

Every affair, or case of cheating is different, so the answer is: it depends on the circumstances.

Not impossible but very hard. Needs to be complete transparency with each other to rebuild trust and both committed to doing this.

Just take the Clintons. Bill cheated before, Bill cheated after. Hillary could care less.

A friend of mine told to his unloyal soon to become ex wife: Without you our marriage will not be the same

Complicated issue. I have friends that after counseling their marriage and sex life was much improved.

I doubt it for most. There are always exceptions, but generally, when the trust has gone, it’s gone.

it can
but it will take a lot of time and if both parties works for it

I do not believe so.

No

Not just marriage, but any relationship that is broken after infidelity.
Most times, people can say they forgive, but not forget... and often, the hard feelings remain.
I don't believe a person needs to screw around on another... whatever the reason. doing so will often destroy what was only broken before.
If a relationship/marriage is that bad off, go for counseling or tell the person it's over. If you can go for counseling after the deed, you surely can go before.

Nope