He had originally fallen asleep next to her so she didn't think anything of it when she felt him reach from behind her and start touching her.
She went along with it and still facing away, had sex with him.
But when Abigail returned from the bathroom she realised it was not her boyfriend at all, it was Grant, whose real name is Donald Grant Ward.
"I remember him grinning at me. It was a freaky image," she told Buzzfeed News.
"I was just kind of — I was frantic. I didn't know what was going on.
"I was like, 'I feel violated. This feels wrong. But I don't know if it's illegal'."
After Abigail's boyfriend confronted Grant, the couple went to the police.
In an interrogation, Grant admitted he believed that Abigail thought he was her boyfriend because she got "very close" to him.
Police charged him with two counts of rape in February 2017.
Grant's defence lawyer Kirk Freeman said he never should have been charged with that and police should have prosecuted for what they knew they could.
Freeman argued that while Grant's conduct was "ungentlemanly" it wasn't illegal under Indiana law.
In Indiana, and 40 other states including New York, rape is legally defined as sex compelled through force or threats or if the victim can't consent or is unaware that the sex is occurring. Consent isn't expressly defined in the statute.
After two days of testimony and a few hours of deliberation, Grant was acquitted and the rape charge was wiped from his record.
Buzzfeed wrote Freeman was "mimicking a whining child" when he explained the "overcharging" by prosecutors.
"It makes absolutely no sense if you're 'Boo hoo hoo the victim, boo hoo hoo hoo'," he said.
"If your concern was for her, then why not prosecute for what you could do rather than what you knew was way out of bounds?"
He also equated her case to women who sleep with men who pretend to be star football players.
Abigail said she felt like she wasted a year of her life.
"They told me the specific charges and I didn't think to question them, which in hindsight I should have," she said.
Kirkman said the case should have been sexual battery, however that charge would have only covered the groping and not the sex.
They also carry very different sentences.
If you're in danger NOW:
• Phone the police on 111 or ask neighbours of friends to ring for you.
• Run outside and head for where there are other people.
• Scream for help so that your neighbours can hear you.
• If you are being abused, remember it's not your fault.
Where to go for help or more information:
• NZ Police
• Help Auckland 24/7 helpline 09 623 1700
• Rape Prevention Education
• Wellington Help 24/7 crisisline 04 801 6655, push 0
• Male Survivors of Sexual Abuse
• Women's Refuge: Free national crisis line operates 24/7 - 0800 REFUGE or 0800 733 843 www.womensrefuge.org.nz
• Shine, free national helpline 9am- 11pm every day - 0508 744 633 www.2shine.org.nz
• Shakti: Providing specialist cultural services for African, Asian and Middle Eastern women and their children. Crisis line 24/7 0800 742 584
• White Ribbon: Aiming to eliminate men's violence towards women, focusing this year on sexual violence and the issue of consent. www.whiteribbon.org.nz