After making a successful pitch in an on-field marriage proposal Friday, Tulane’s J.P. France threw a bunch of good ones in his final start at Turchin Stadium.

But just like Corey Merrill in the series opener against Houston, France had absolutely nothing to show for them.

Left-hander Trey Cumbie threw a complete-game, five-hit shutout Saturday, and the Cougars capitalized on almost all of their chances, winning 4-0 to clinch the series while the Green Wave continued its late-season freefall.

Tulane (23-28, 10-10 American Athletic Conference), which was 8-2 in league play after winning at Houston on April 21, is three games behind co-leaders Houston (33-17, 13-7) and Central Florida with four to play.

The Wave also lost to Houston for the fourth straight time in its rapid plummet from first place to fifth.

Don’t blame France (6-5), who allowed six hits and two earned runs in seven innings. He was a hard-luck loser for the first time in seven conference starts, entering at 4-0 with two no-decisions.

“Every loss is rough,” he said. “This one is heartbreaking because we needed this win really badly.”

No leadoff hitter reached against Cumbie (8-1), and Tulane never got past second base. The Wave was coming off a 15-3 loss late Friday night, one in which it blew a 3-1 lead in the eighth inning. On Saturday, Tulane failed to score for only the second time this year.

“I was just a little bit worried about our gas today,” coach Travis Jewett said. “I just didn’t feel like we played with a lot of pizzazz.”

Houston received a free pass to third base on two passed balls and a wild pitch, scoring on two safety squeezes, a groundout RBI and a steal of home against freshman reliever Keagan Gillies.

France also struck out five guys looking.

“It stinks when you let a guy like J.P. down,” senior first baseman Hunter Williams said. “He gave everything he had and pitched plenty well enough to win, and we didn’t do anything to support him.”

Williams actually doubled twice, and his second one appeared to be headed out of the park before the wind knocked it down.

“I knew the wind was blowing a little bit, but I didn’t think it was going to hold it up that much,” he said. “I thought that one was well out of here.”

Nothing has gone right for the Wave since France’s pre-game proposal Friday night, when girlfriend Stephanie Davis said yes.

After luring her to the field because France’s father was throwing the opening pitch on his birthday, he got down on one knee and revealed the ring in a cut baseball.

“I think everybody in Louisiana knew about it except her,” France said. “It felt like 500 pounds got lifted off my shoulder, and I had to turn around and come pitch today and get my mind right.”

That’s what his teammates will have to do Sunday as they try to salvage the series finale.

“We have to have fun,” Williams said. “We talked about it in the postgame huddle. Come on, guys. Let’s just relax and play these for us for the rest of the regular season, and then go to work in the conference tournament.”